Conversion Functions


For instance. We are working with an integer. And now we want to convert that integer into a string. We need a conversion function.


AutoLISP has got eleven conversion functions. Here they are:


(angtos <angle> [<mode> [<precision>]])


This function converts an angle into a string. The angle is a real number in radians. The result depends on the mode and the precision.


Mode Description


0 Degrees
1 Degrees/minutes/seconds
2 Degrees (400)
3 Radians
4 Land units


The precision argument give the number of decimals. The mode and precision argument are in the system variables AUUNITS and AUPREC.


Examples:


(setq p1 (list 500 133))
(setq p2 (list 240 133))
(setq an (angle p1 p2))


(angtos an 0 0) "180"
(angtos an 0 4) "180.0000"
(angtos an 1 4) "180d0'0"
(angtos an 3 4) "3.1416r"
(angtos an 4 2) "W"


(rtos <number> [<mode> [<precision>]])


Now a real number is converted into a text. The units and precision depend on the arguments for mode and precision.


Mode Description


1 Mathematical
2 Decimal
3 Feet and decimal inches
4 Feet and fractional inches
5 Divisions


The mode and the precision arguments can be found in the system variables LUNITS and LUPREC.


Examples:


(rtos 17.5 1 4) "1.7500E+01"
(rtos 17.5 2 2) "17.50"
(rtos 17.5 3 2) "1'-5.50"
(rtos 17.5 4 2) "1'-5 1/2"
(rtos 17.5 5 2) "17 1/2"


(itoa <integer>)


Now an integer is converted into a text.


Examples:


(itoa 33) "33"
(itoa -17) "-17"


(atoi <text>)


A text is converted into an integer.


Examples:


(atoi "97") 97
(atoi "-3") -3
(atoi "3.9") 3


(atof <text>)


A text is converted into a real number.


Examples:


(atof "97.1") 97.1
(atof "-3") -3.0


(fix <number>)


This function translates a number into an integer.


Examples:


(fix 3) 3
(fix 3.7) 3


(float <number>)


Here a number is translated into a real number.


Examples:


(float 3) 3.0
(float 3.75) 3.75


(list <expression>)


A list is created with a number of loose expressions. It is often used to create a 2D point or 3D point.


(list 'a 'b 'c) (A B C)
(list 'a '(b c) "text") (A (B C) "text")
(list 3.9 6.7) (3.9 6.7)


(ascii "text")


The ASCII value of the first character of the text is given.


(ascii "a") 97
(ascii "A") 66
(ascii "all") 97


(chr <number>)


The number is an ASCII value. The corresponding character is givne back.


Examples:


(chr 65) "A"
(chr 66) "B"
(chr 97) "a"


(read <text>)


This function gives back what has been read. The text cannot contain spaces. What is after the space is ignored.


(read "LISP") LISP
(read "A") A


Exercise:


Create an AutoLISP program, that creates the following parking spot. Do you see? The sizes for the length, width, and angle are given.








This is how the AutoLISP program works:


Command: PRKSP
Width/Length/Angle/<starting point>:W
Width <default>: width is entered
Width/Length/Angle/<starting point>:L
Length <default>: length is entered
Width/Length/Angle/<starting point>:A
Angle <default>: angle is entered
Number of parking spots <default>: number is entered


Take care. The AutoLISP program is going to be very big. So make separate functions for entering the width, length, and angle.


Exercise


Let's write an AutoLISP program. This is the drawing that is created by the AutoLISP program.




Two points are picked. The circle is drawn in one point. And as line goes to the other point, starting in the first point.


The user enters what text is to be drawn in the circle. And a box is drawn around the text. The TEXTBOX function is used.

Graphical Screen Functions

These functions can be used to make changes to the graphical screen. The graphical screen is the drawing area of AutoCAD.


(grclear)


This function is used to clean th active view port of the drawing area. The information is not erased, but made invisible.


If the REDRAW command is used, then the information is visible again.


(grdraw <p1> <p2> <color> [<highlight>])


This function is used to draw a line between the points p1 and p2. The points can be 2D points and 3D points.


The color argument sets the color of the line. If the color argument is -1, then the line is drawn in the color in a complimentary color.


If another vector is drawn over the same points with the color, then the complete line is made invisible.


If the highlight argument is present and unequal to zero, then the line is drawn in a highlighted format.


(grtext [<box> <text> [<higlight>])


With this function you can write text to the screen menu of AutoCAD. I'm afraid screen menus are no longer used. So forget it.


(grread [<track>])


With this function you can read input from devices such as keyboard, digitizer, mouse, etc. But most of the time GET functions are used.


If a mouse is used, then this is what could be given back by the GRREAD fucntion:


(3 (-13.9732 13.0249 0.000000))


The first element is the the code of the device. These are the codes that are available:


2 Keyboard and the ASCII code of the character.


3 Mouse. The point is put in a list.


4 Screen menu cell with the number of the cell.


5 A list of the point for the drag mode. Only if the TRACK argument is unequal to nil.


6 Button number of the mouse.


7 Selected item in TABLET 1 menu.


8 Selected item in TABLET 2 menu.


9 Selected item in TABLET 3 menu.


10 Selected item in TABLET 4 menu.


11 Selected item in AUX 1 menu.


12 Point of the mouse.


13 Selected screen menu item.


(menucmd <text>)


This is another function that works with the screen menu. We are not using it. So you can forget about it.


Exercise


Now we are going to create an AutoLISP program, that draws circles and lines. The center points of the circles are picked.


To create the AutoLISP program the WHILE function is used. Here is the drawing that is created. Four circles have been drawn. But more circles could be drawn.

Graphical Screen Functions

These functions can be used to make changes to the graphical screen. The graphical screen is the drawing area of AutoCAD.


(grclear)


This function is used to clean th active view port of the drawing area. The information is not erased, but made invisible.


If the REDRAW command is used, then the information is visible again.


(grdraw <p1> <p2> <color> [<highlight>])


This function is used to draw a line between the points p1 and p2. The points can be 2D points and 3D points.


The color argument sets the color of the line. If the color argument is -1, then the line is drawn in the color in a complimentary color.


If another vector is drawn over the same points with the color, then the complete line is made invisible.


If the highlight argument is present and unequal to zero, then the line is drawn in a highlighted format.


(grtext [<box> <text> [<higlight>])


With this function you can write text to the screen menu of AutoCAD. I'm afraid screen menus are no longer used. So forget it.


(grread [<track>])


With this function you can read input from devices such as keyboard, digitizer, mouse, etc. But most of the time GET functions are used.


If a mouse is used, then this is what could be given back by the GRREAD fucntion:


(3 (-13.9732 13.0249 0.000000))


The first element is the the code of the device. These are the codes that are available:


2 Keyboard and the ASCII code of the character.


3 Mouse. The point is put in a list.


4 Screen menu cell with the number of the cell.


5 A list of the point for the drag mode. Only if the TRACK argument is unequal to nil.


6 Button number of the mouse.


7 Selected item in TABLET 1 menu.


8 Selected item in TABLET 2 menu.


9 Selected item in TABLET 3 menu.


10 Selected item in TABLET 4 menu.


11 Selected item in AUX 1 menu.


12 Point of the mouse.


13 Selected screen menu item.


(menucmd <text>)


This is another function that works with the screen menu. We are not using it. So you can forget about it.


Exercise


Now we are going to create an AutoLISP program, that draws circles and lines. The center points of the circles are picked.


To create the AutoLISP program the WHILE function is used. Here is the drawing that is created. Four circles have been drawn. But more circles could be drawn.

Text Screen Functions

Text Screen Functions


Hari Raya


Sorry. I could not add a new post to my blog for two weeks. It was not my fault. It has to do
with Hari Raya.


I live in Malaysia. And you find a lot of Muslims here. They celebrate Ramadan every year. Ramadan is a month of fasting.


When Ramadan is over, then we have Hari Raya. It lasts a couple of days, when everybody has a national holiday.


But the majority of the people take a holiday. And if they have a shop, they close it. Even Chinese shops and Indian shops are closed.


I do my Internet in an Internet cafe. And my Internet cafe was closed too. So I could not add a new post to my blog.


Don't worry. I keep on adding new posts to my blog. I didn't give up. I still have a lot that I want to say.


Text Screen Functions


In AutoLISP we have the following functions that can be used for giving an AutoLISP program a presentation. They are:


- Text screen functions
- Graphical screen functions
- Text functions
- Conversion functions


Now we are going to talk about the text screen functions. Later we are going to talk about the other functions.


(graphscr)
(textscr)


You can switch from the text screen to the graphic screen with the (graphscr) functions and go to the text screen with the (textscr) function.


System Variables


AutoCAD works with system variables. You can check the value of a system variable with the following function:


(getvar <variabele name>)


Examples:


(getvar “dwgname”) TEST
(getvar “cmdecho”) 1


Some system variables are read only. You cannot change their value. But if you can, you can change the value with:


(setvar <variable name> <value>)


Examples:


(setvar “filletrad” 200) 200
(setvar “cmdecho” 0) 0


It is advisable to set the system variable to its original value after the value has been changed. This is how it can be done:


(setq ce (getvar “cmdecho”)
(setvar “cmdecho” 0)
(setvar “cmdecho” ce)


Printing Data


(princ <expression> [<file description>])


This function writes the expression to the text screen and gives as a result the expression. The expression can be a text or a number.


The file description argument is optional and is used if the expression is written to an external file. We will talk about it later.


Examples:


(setq a 123)
(setq b '(a))


(princ 'a) A
(princ a) 123
(princ b) (A)
(princ “Hello”) “Hello”


If the expression is a text, then control codes can be added to it. The following control codes are available.


\\ the \ character
\e escape
\n new line
\r return
\t tab
\nnn the character with the octal code nnn


The PRINC function can also be used without an argument. Then an empty string is written to the screen. That is often at the end of a program.


Example:


(defun c:setng ()
(setvar “lunits” 4)
(setvar “blipmode” 0)
(princ)
)


After the AutoLISP program has been loaded into AutoCAD it is started by typing its name at the command prompt.


At the end of the AutoLISP program the command prompt is shown again without any additional information. There is no 0.


(prin1 <expression> [<file description>])


This function is the same as the previous function, but control codes are not evaluated.


Examples:


(setq a 123)
(setq b '(a))


(princ 'a) A
(princ a) 123
(princ b) (A)
(princ “Hello”) “Hello”


(print <expression> <file description>)


This function is the same as the previous function. But the expression is print on a new line and after the expression is a tab.


(prompt <text>)


Now you can only print a text to the text screen. The function prints the text and gives back nil.


Example:


(prompt “New value”) New value


Exercise


For this exercisxe the REPEAT function is used. Write an AutoLISP program, that draws five circles with the number of the circle in it.


This is the drawing that is created by the AutoLISP program.

Repetition Functions

Repetition Functions


Now we come to the repetition functions. They are very important. Repetition functions are often used in AutoLISP programs.


Here they are:


WHILE Function


(while (<test> <expression> …)


This function performs a test at the beginning. If the test gives nil, then the expressions are evaluated.


Example:


(defun c:numbr (/ nr)
(setq nr 1)
(while (<= nr 5)
(princ "\nNumber: ")
(princ nr)
(setq nr (1+ nr))
)
(princ)
)
(c:numbr)


At the start of the AutoLISP program the variable NR is given the value 1. The value of the variable is tested at the beginning of the WHILE function.


As long as the value is less or equal to five, then the expressions in the WHILE function are evaluated.


This is given back by the AutoLISP program:


Number: 1
Number: 2
Number: 3
Number: 4
Number: 5


Repeat Function


(repeat <number> <expression> …)


Now the number of repetitions can be specified.


Example:


(princ "\n")
(defun c:repfc ()
(repeat 4
(princ "-")
)
(princ)
)
(c:repfc)


This is given back by the AutoLISP program:


----


Foreach Function


(foreach <name> <list> <expression> …)


This function goes through a list and gives every element of the list a name. The expression is performed for every name.


Example:


(foreach n (list 1 2 3) (* n 2))


The AutoLISP line gives back 6. The number 3 is multiplied with 2.


Exercise:


We have been talking about predicates, test functions and repetition functions. Here is an exercise to use what has been taught.


Write the SLINE AutoLISP program. The following prompts will show up:


Command: SLINE
Color/Linetype/<first point>: C
Color: 1
Color/Linetype/<first point>: L
Linetype: Hidden
Color/Linetype/<first point>: 100,100
Close/<next point>: 300,300
Close/<next point>: C
Command:

Test Functions

Test Functions


AutoLISP has got two text functions. They are:


- IF function
- COND function


IF Function


(if <expression> <then> <else>)


The expression is evaluated. If it is true, then the THEN part is performed. If not, then the ELSE part is performed.


Examples:


Function: Gives:


(if (= 1 3) "Yes" "No") "No"
(if (= 2 (+ 1 1) "Yes") "Yes"
(if (= 2 (+ 3 4) "Yes") nil


The THEN part or the ELSE part of the IF function can only contain one expression. If more there are more expressions, then PROGN is used.


Example:


(if (= a b)
(progn
(setq a (+ a 10))
(setq b (+ b 10))
)
(progn
(setq a (- a 10))
(setq b (- b 10))
)
)


Here is another example of how the IF function can be used. Now we have an AutoLISP program. A line is drawn and a circle and a text.


(defun c:ball1 (/ p1 p2 an tx aw ht)
(setq p1 (getpoint "\nFirst point:")
p2 (getpoint p1 "\nSecond point:")
an (angle p1 p2)
)
(initget 1 "Yes" No")
(setq aw (getkword "Text (Yes/No)? "))
(if (= aw "Yes")
(setq ht (getdist "\nHeight: ")
tx (getstring "\nText: ")
)
(setq ht (getdist p1 "\nRadius: "))
)
(command "line" (polar p1 an ht) p2 ""
"circle" p1 ht
)
(if (= aw "Yes")
(command "text" "m" p1 ht 0 tx)
)
)


COND Function


(cond (<text1> <result1> …)


This function is used to perform an action depending on the value of a variable. Here is an AutoLISP program that shows it.


If is the program from before. But now you can draw a circle, a square, or a triangle. You choose in the beginning.


(defun c:ball2 (/ p1 p2 an ht tx aw)
(setq p1 (getpoint "\nFirst point: ")
p2 (getpoint p1 "\nSecond point: ")
an (angle p1 p2)
ht (getdist "\nHeight text: ")
tx (getstring "\nText: ")
)
(initget "Cir Tri Quadr")
(setq aw (getkword "\nTriangle/Quadrant/
<Circle>: ")
)
(command "line" (polar p1 an ht) p2 "")
(cond
((= aw "Tri")
(command "polygon" 3
p1
"c"
(polar p1 an ht)
)
)
((= aw "Quadr")
(command "polygon" 4
p1
"c"
ht
)
)
(T
(command "circle" p1 ht)
)
)
(command "text" "m" p1 ht 0 txt)
)

Predicates Or Boolean Expressions

Predicates Or Boolean Expressions


We have done parametric drawing. Now we are going to talk about predicates or boolean expressions. AutoLISP has got a lot of them.


A predicate gives back true or lase. True is presented as T and false or untrue is presented as nil.


Predicates


(= <atom> <atom> …)


This function checks if two or more texts and numbers are equal. If so T is given back. Otherwise nil is given back.


Examples:


(= 4 4.0) T
(= 20 300) nil
(= 2.4 2.4 2.4) T
(= 400 500 400) nil
(= “I” “I”) T


(/= <atom> <atom>)


This fiction is the same as the one from before. Except. T is given back if untrue and nil is given back if true.


Examples:


(/= 10 20) T
(/= “You” “You”) nil
(/= 5.34 5.44) T

(< <atom> <atom>)


This function works on numbers and texts. T is given back if the first atom is smaller than the second atom.


Examples:


(< 10 20) T
(< “b” “c”) T
(< 357 2.4) nil
(< 2.3 88) T
(< 2.3 4.4) T


(<= <atom> <atom>)


Now there is checked if both atoms are equal or the first atom is smaller than the second atom.


Examples:


(<= 10 20) T
(<= “b” “b”) T
(<= 357 33.2) nil
(<= 2.9 9) T


(> <atom> <atom>)


Now there is checked if the first atom is more than the second atom. As before. The atoms can be numbers and texts.


Examples:


(> 120 17) T
(> “c” “b”) T
(> 3.5 1792) nil
(> 77.4 4.2) T
(> 77.4 4) T


(>= <atom> <atom>)


The same as before. Except now there is checked if the atoms are equal or the first atom is more than the second atom.


Examples:


(>= 120 17) T
(>= “c” “c”) T
(>= 3.5 1792) nil
(>= 77 4 4.0) T
(>= 77 4 9) nil


(equal <expression1> <expression2> <fuzz>)


The expressions are checked. Are they equal or not. If working with numbers, you want to introduce a fuzz.


Even if numbers are supposed to be equal, there can be a little difference between them. The difference is specified in the fuzz.


Examples:


(setq f1 '(a b c))
(setq f2 '(a b c))
(setq f3 f2)


(equal f1 f3) T
(equal f3 f2) T


(setq a 1.23456)
(setq b 1.23457)


(equal a b 0.00001) T


(eq <expression1> <expression2>)


This function is used to check if two lists are equal. Are they bound to the same object? If so T is given back.


Examples:


(setq f1 '(a b c))
(setq f2 '(a b c))
(setq f3 f2)


(eq f1 f3) nil
(eq f1 f3) T


(atom <item>)


This function gives back T if the item is an atom and not a list. If it is a list, then nil is given back.


Examples:


(setq a '(x y z))
(setq b 'a)


(atom 'a) T
(atom a) nil
(atom 'b) T
(atom b T
(atom '(a b c)) nil


(listp <item>)


You want to check if the item is a list. Use this function for doing that. It gives back T if it is an item.


Examples:


(listp '(a b c)) T
(listp 'a) nil
(listp 4.343) nil


(boundp <item>)


Use this fucntion to see whether the item has got a value. The value can be a number or a text.


Examples:


(setq a 2)
(setq b nil)


(boundp 'a) T
(boundp 'b) nil


(numberp <item>)


This function checks if the item is an integer number or an real number.


Examples:


(numberp 4) T
(numberp 3.824) T
(numberp “Hallo”) nil
(numberp (setq a 10)) T


(minusp <item>)


Is the item a negative integer number or a negative real number?


Examples:


(minusp -1) T
(minusp (- 1 4)) T
(minusp 830.3) nil


(zerop <item>)


Is the value of the item zero?


Examples:


(zerop 0) T
(zerop (- 4 4.0)) T
(zerop 0.00001) nil


(and <expression> …)


This function checks if all expressions have a value of that is not nil. If one value is nil, then it gives back nil.


Examples:


(setq a 100)
(setq b nil)
(setq c “text”)


(and 1.4 a c) T
(and 1.4 a b c) nil


(or <expression> …)


This function checks if at least one expression is unequal to nil. If all expressions are equal to nil, the it gives back nil.


Examples:


(setq a 100)
(setq b nil)
(setq c “text”)


(or nil a b c) T
(or nil b '()) nil




(not <item>)


The result of this function is T is the value of the item is nil. Otherwise it is is nil.


Examples:


(null <item>)


Now there is checked if the value of the item is nil. If so then T is given back.


Examples:


(setq a 123)
(setq b nil)
(setq c “text”)


(null a) nil
(null b) T
(null c) nil
(null '()) T


(type <item>)


Here the type of the item is found. These are the types that are known in AutoLISP.


REAL real number
FILE file descriptor
STR text
INT integer number
SYM symbol
LIST list and user function
SUBSR internal AutoLISP function
PICKSET selection set
ENAME entity name
PAGETB function page table


Examples:


(setq a 123)
(setq r 3.5)
(setq t “text”)
(setq l '(a b c))


(type 'a) SYM
(type a) INT
(type r) REAL
(type t) STR
(type l) LIST
(type *) SUBR

Parametric Drawing

We can create AutoCAD drawings using AutoLISP. Here is an AutoLISP program that does the job. The name of the program is NEWDR.LSP.


The AutoLISP Program


(defun c:newdr (/ p1 p2 p3 p4 p5 p6 p7 sd ts ws)
(setvar “cmdecho” 0)
(setq p1 (getpoint “\nPosition door: “)
sd (getdist “\nStructural dimension: “)
ws (getdist “\nWidth style: “)
ts (getdist “\nThickness style: “)
p2 (polar p1 0 ts)
p3 (polar p2 (/ pi 2) ws)
p4 (polar p3 pi ts)
p5 (polar p2 0 sd)
p6 (polar p3 0 sd)
p7 (polar p3 (/ pi 2) sd)
)
(command “pline” p1 “w” 0 0 p2 p3 p4 “c”)
(command “copy” “l” “” p1 p5 “”)
(command “pline” p2 p5 “”)
(command “copy” “l” “” p2 p3 “”)
(command “pline” p3 p7 “”)
(command “arc” p6 “c” p3 p7)
(command “zoom” “a”)
(command “zoom” “0.8x”)
(setvar “cmdecho” 1) (princ)
)
(c:newdr)


Using the program a door will be drawn. See how the door looks. As you can see. The door has different sizes and a position.

Copy The AutoLISP Program


That is so good about the listing of an AutoLISP program. You can save it on your hard disk and use it again. Copy the program to a text file.


That is important. When the listing of an AutoLISP program is saved, it is saved with the extension LSP. It can be loaded into your CAD program.


Loading The AutoLISP Program


Let's talk about how to load an AutoLISP program into the AutoCAD program. That must be done first before you can use the AutoLISP program.


I will talk about loading the AutoLISP program into IntelliCAD. Loading it into AutoCAD is done in the same way. So don't worry.


You are in IntelliCAD. Click on Tools in the menu. In the pop-up menu click on Load Application. The Load Application files dialog box is displayed.


In the dialog box click on the Add File button. You can go to different folders and you can select the AutoLISP file that you want to load.


Click on the file. And click on the Open button. You come back into the Load Application file dialog box. Click in the Load button.


The AutoLISP file is now loaded into IntelliCAD. And you can start it by typing its name at the prompt.


Starting Automatically


Before I talk about the AutoLISP program, I want to say something about what has been added to the program. At the end you see:


(c:newdr)


Through that line the AutoLISP starts as it has been loaded into IntelliCAD. As you can see. The name of the AutoLISP program is in the line.


Functions


In the AutoLISP program we find functions. The first function we find it the DEFUN function. Here is the syntax of the DEFUN function:


(defun <symbol> <argument list> <expression> ...)


This how the DEFUN function is used for defining an AutoLISP function. SYMBOL is the name of the new AutoLISP function.


Arguments


In the argument list you find all the arguments that the new AutoLISP function needs to run properly. If not there, then an error occurs.


Local Variables


In the argument list you can find a slash. After the slash comes a list of variables. Those variables are local variables.


The local variables only have a value in the function. Outside the function they have no value. Or the value of them is nil.


If no argument list is given then the symbol of an empty list must be used. This is how that symbol looks like: ().


Variables that are not defined as local have a value outside the function. They have a value when the function is no longer running.


Here are some examples:


(defun funct (x y) – the function has two arguments


(defun funct (/ a b) – the function has two local variables


(defun funct (z / a) – the function has no argument and one local variable


(defun funct () - the function has no arguments



In the AutoLISP function the GETPOINT and GETDIST functions are used. To get information. In a separate chapter we talk about the functions.


As you can see. AutoCAD commands were used in the AutoLISP program. I will talk about using AutoCAD commands in another report.


Exercise


You now have seen how an AutoLISP program is created. You have seen how distances can be entered and how AutoCAD commands are used.



Go ahead. Write your own program. This time the program is going to draw a house. Enter the sizes of the house.

Arithmetic And Geometric Functions

Arithmetic Functions


That is important. In an arithmetic function the mathematical symbol always comes before the arguments.


(+ <number> <number> ...)


The plus sign is a mathematical symbol.


Examples:


Function Gives back


(+ 1 2) 3
(+ 12 13) 25
(+ 1 2 3 4 5) 15


(- <number> <number> ...)


Examples:


Function Gives back


(- 50 40) 10
(- 40 30 5 0) 5
(- 10 20) -10


(* <number> <number> ...)


Examples:


Function Gives back



(* 2 3) 6
(* 12 15 2) 360
(* 3 -4.5) -13.5


(/ <number> <number> ...)


Function Gives back



(/ 100 2) 50
(/ 100 2.0) 50.0
(/ 100 20 2) 5


(1+ <number>)


Example:



Function Gives back



(1+ 5) 6


(1- <number>)


Example:



Function Gives back



(1- 10) 9


(abs <number>)


This function gives the absolute value of the number. The number can be a real number of an integer.


Examples:


Function Gives back


(abs 100) 100
(abs -97.25) 97.25


(max <number> <number> ...)


This function gives back the number that is the maximum of all the numbers. The number can be a real number or an integer.


Examples:


Function Gives back


(max 12 20) 20
(max 5,5 7) 7


(min <number> <number> ...)


This function is the opposite of the previous function. Now the minimum number is given back. The number can be a real number or an integer.


Examples:


Function Gives back


(min 4.07 -144) -144
(min 88.5 19 5) 5


(gcd <number> <number>)


Now we are going to do a complicated calculation.With this function the greatest common divisor is found. The numbers are integers.


Examples:


Function Gives back



(gcd 81 57) 3
(gcd 12 20) 4


(rem <number> <number> ...)


This function calculates how much remains after a division. The numbers can be integers and real numbers.


Examples:



Function Gives back



(rem 42 12) 6
(rem 9 4) 1



(exp <number>)


This function raises e to the mach of the number. The number can be an integer as a real number. The result is always positive.


Examples:


Function Gives back



(exp 1) 2.71828
(exp 2.2) 9.02501
(exp -0.4) 0.67032


(expt <base> <exponent>)


Now the base number is raised to the mach of the exponent number. The base and the exponent can be integers and real numbers.


Examples:


Function Gives back



(expt 2 4) 16
(expt 3.0 2) 9.0


(sqrt <number>)


This function calculates the square root of the number. The number can be an integer as well as a real number.


Examples:


Function Gives back



(sqrt 9) 3
(sqrt 2.0) 1.41321


(log <number>)


This function gives as result the natural logarithm of the number. The number can be an integer as well as a real number.


Examples:


Function Gives back



(log 4.5) 1.50408
(log 1.22) 0.198851


pi


This is no function but a constant number. The value of the number is 3.1415926.


Geometric Functions


(cos <angle>)


This function calculates the cosinus of an angle. The angle is expressed in radians.


Examples:



Function Gives back



(cos 0) -1
(cos pi) 1



(sin <angle>)


The same as before. Except this time the sinus of an angle is calculated. The angle is expressed in radians.


Examples:


Function Gives back



(sin 1.0) 0.841471
(sin 0,0) 0.0


(atan <number> [<number>])


If the second number is not present, then the function gives back the tangent of the first number in radians.


The number of the angle can be between pi and -pi,


Examples:


Function Gives back



(atan 0.5) 0.463648
(atan 1.0) 0.785398
(atan -1.0) -0.785398


If the second number is present, then the function gives back the inverse tangent of the quotient of the two numbers.


Examples:



Function Gives back



(atan 2.0 3.0) 0.588003
(atan -2.0 3.0) -0.68003
(atan -2.0 -3.0) -2.55359
(atan 1.0 0.0) 1.570796
(atan -0.5 0.0) -1.570796


(angle <point1> <point2>)


The function calculates the angle of the straight line going from point1 to point2. It calculates the angle between the line and the active UCS.


UCS stands for User Coordinate System. And the angles are measured counter clockwise. And the angle is given in radians.


Examples:


Function Gives back



(angle '(1.0 1.0) '(1.0 4.0)) 1.5708
(angle '(5.0 1.33) '(2.4 1.33)) 3.14159


(distance <point1> <point2>)


The function gives the distance between the two points. The distance is given in screen units.


If the value of the FLATLAND system variable is unequal to zero, then 2D points are expected. If a 3D point is used, then the Z value is ignored.


Examples:
Function Gives back



(distance '(1.0 2.5 3.0)
'(7.7 2.5 3.0)
) 6.7
(distance '(1.0 5.0)
'(1.0 15.0)
) 10.0


(inters <point1> <point2> <point3> <point4> [<on>])


The function calculates where the lines between point 1 and point 2 and point 3 and point 4 cross. A point is given back.


When the optional argument ON is present and nil. Then the two lines are considered to be infinite.


Examples:


(setq p1 (list 1.0 1.0)
p2 (list 9.0 9.0)
p3 (list 4.0 1.0)
p4 (list 4.0 2.0)
)


Function Gives back



(inters p1 p2 p3 p4) nil
(inters p1 p2 p3 p4 T) nil
(inters p1 p2 p3 p4 nil) (4.0 4.0)


(polar <point> <angle> <distance>)


This function gives as a result a point that is under an angle from the point that has been given and on the distance.


Example:


Function Gives back



(polar '(1.0 1.0) 0 4.0) (5.0 1.0)


(osnap <point> <mode>)


Depending on the value of the text of the mode a point is calculated. These are the modes there
are:


Mode Description


”nea” Nearest snap
”endp” Endpoint snap
”midp” Midpoint snap
”centre” Center snap
”perp” Perpendicular snap
”tan” Tangent snap
”quad” Quadrant snap
”int” Insertion point snap
”pnt” Point Snap
”int” Intersection snap



Example:


Function



(setq pt (osnap pt “nea”))


Exercises



1. Write the following arithmetic functions:


- 12 plus 13
- 8 times 5
- 200 divided by 4
- What is maximum of 12, 25 3 2, 94?
- What is the greatest common divisor of 256 and 326?
- What is the 8^th power of 3?


2. Using geometric functions:


- What is the angle of a horizontal line? From left to right and from right to left.
- What is the distance between the points 10,20 and 40,50?
- What point is found starting in punt 10,20 and under an angel of 45 degrees and over a distance of 25?

Start

In my blog I offered my readers from Mislay that Iwould give them an AutoLISP course free of charge.That is how it was on March 14 this year.

I have 175 readers from Malaysia of my blog. But none of them came to me for the free AutoLISP 

course. I don't understand why.

Were they thinking I was offering a free AutoLISP course as as trick to get money from them? Nobody told me.

Sure. They had to pay me. I wanted them to pay me back my travel expenses. That is all. But was eventhat too much for them?

Anyway. I not only have readers of my blog from Malaysia. They come from all over the world. This iswhat I'm going to do.

I'm going to publish my AutoLISP course in this blog. And yes. It is free of charge. You don't have to pay me any money.

The course consists of the following twelve chapters. You will get them in the coming weeks. Every week you will get a chapter.

1.  Introduction 
2.  Basic Concepts 
3.  Arithmetic And Geometric Functions 
4.  Parametric Drawing 
5.  Predicates And Repeat Functions 
6.  Presentation Of Routines 
7.  List Functions 
8.  AutoLISP And AutoCAD Database 
9.  System Management
10.  System Variables 
11.  DXF Table 
12.  Answers 

At the end of each chapter there are exercises. The answers of the exercises will be given to you inthe last chapter.

This is only an AutoLISP course. But. Talking about AutoLISP. We also can deal with dialog boxes. 

That is next.

I will also publish a dialog boxes course. I will tell you later about the dialog boxes course. I 

will give you the chapters.

How To Get Your AutoCAD Drawings Right Away

You are working with AutoCAD. Or any CAD program. You know how it is. It takes a lot of time before your drawing has been created.

And then. After your drawing has been created. You cannot use it right away. The drawing must be checked. And that takes time too.

Big Disadvantage

Waiting for your CAD drawing before it is finished. And then the time that checking takes. That is a big disadvantage.

Is that how it always is? Is there no way that the waiting can be avoided? Is there a quicker way of getting your CAD drawing?

A Quicker Way 

There is a quicker way. There is no need for waiting for hours before your CAD drawing is finished and checked.

Get an AutoLISP program. An AutoLISP program can create parts of your CAD drawing. It can even create complete CAD drawings.

If the AutoLISP program is creating parts of your CAD drawing, you are saving a lot of time. The CAD operator is quicker.

The AutoLISP program creating a complete CAD drawing. That is even better. You get your CAD drawing in less than five seconds.

And working with the CAD program is very easy. Anybody can work with the CAD program. Even non CAD operators.

CAD Operators

I'm not saying that you must do that. I'm not saying to get rid of all your CAD operators. But maybe you can do with less of them.

I think. Even if you are working with a lot of CAD programs. You still need CAD operators. Not everything is done automatically.

The Point

That is the point of this post. There is no need for waiting for hours before your CAD drawing is finished. You can save a lot of time.

Something Completely Different


Here is something completely different from what you normally read in this blog. It is an imagination.


Imagine this. One day you wake up and you are a millionaire! Look at how different your life will be:


- You no longer have to worry about your debts, bills, and slaving for money.


- You can spend your time doing things you love, spend your time with your beloved family and friends.


- You no longer have to worry about money or have to be poor again. Never again living the life you used to have.


Do you want to be a millionaire? Make your dream lifestyle came true. Here's your chance to be a millionaire. Check this out.


Wake Up Millionaire:
http://l1nk.com/rfbzla



To Your Success


Free AutoLISP Course


Sorry. This offer is only for my readers from Malaysia. I want to give an AutoLISP course to them. Free of charge.


I have more than 900 readers. The majority of them is from the USA. More than 500. But I also have readers from Malaysia. About 120.


I don't know what my readers from Malaysia are doing. Are they with an engineering firm or architecture? Or just interested in AutoLISP?


I offer them a free AutoLISP course. It works like this. You let me know if interested and I'll come to your place.


I will give the AutoLISP course at your office. Your people can attend the AutoLISP course. The course consist of 15 lessons.


The first ten lessons are about AutoLISP. All the functions of AutoLISP are explained and there is talked about the system variables.


During the last five lessons we are going to write an AutoLISP program. The people attending the course come with a wish.


That is why this offer is only for my readers from Malaysia. I live in Malaysia. And I do not see how I could travel abroad.


The AutoLISP course is completely free. I will not charge you for the course. But I will ask you to refund my travel expenses.


The people attending the course will get an e-book about AutoLISP. The e-book is a PDF file. What is said in the course, can be found in the book.

What Everybody Ought To Know About Arrays And AutoLISP

You know about arrays. You have arrays in Visual Basic, in C++, and many other programming languages. But AutoLISP?


OK. Let me be very clear. There are no arrays in AutoLISP. But. In AutoLISP. Can you store values that are related?


Oh yes. You can. But is is done in a different way. It is not done in an array. It is done in a list. AutoLISP works with lists.


Arrays


Let me be very clear. Let's start with an array. I start with a one dimensional array. Here is the array:

1	2	3	4
10	20	30	40

You find the following values in the array.


10, 20, 30, 40


So in this one dimensional array you find four values.

	1	2	3
1	10	11	12
2	20	21	22
3	30	31	32

Above you see a two dimensional array. It consists of three rows and three columns. The rows and the columns have been numbered.


You find the following values in the array.


10, 11, 12, 20, 21, 22, 30, 31, 32


So in this array you find nine values. If you want to specify the first value in the second row, then you take this:


array (2,1)


Lists


In AutoLISP we don't have arrays. In AutoLISP we have lists. And like arrays. You have to store all the values in the list.


Let's take a list with the values from the one dimensional array. This is how the list looks.


(10 20 30 40)


But we need to store all the values in the list. This is how we can do it. The name of the list is LS.


(setq ls (list 10 20 30 40))


The list is stored in the variable LS. And that is done with the SETQ function. The LIST function is used to add all the values.


We want to retrieve the values of the list. Suppose we want to find the first value of the list. This is how it is done.


(setq v1 (nth 0 ls))


The number of the first value is zero. The number of the next value is one. Etc. So the number of the last value is three.


OK. Let's make things a little complicated. You saw a two dimensional array. Can we store it in a list in a two dimensional way?


Yes. You can. Of course. You could all the values of the array in a list. But you can also do it in a two dimensional way.


Take the values of each row of the list in a list. This is how it is done:


(setq l1 (list 10 11 12)
l2 (list 20 21 22)
l3 (list 30 31 32)
)


Now we have created three lists. We have created l1, l2, and l3. We turn them into one list. See how it is done.


(setq ls (list l1 l2 l3))


If you enter !ls in AutoCAD, then this is given back by the program:


((11 12 13) (21 22 23) (31 32 33))


Nice. But how can we retrieve the values in the list? Suppose want to know the first value that is in l2. How do we do that?


This is how it is done. We enter at the command prompt:


(setq vl (nth 0 (nth 1 ls)))


First we find the second list in the ls variable. And then we take the first element of the second list. Do you see?


Three Dimensional Lists


Sure. You want to confuse me. You want to make my life very difficult. Now you want to know about three dimensional arrays.


You want to know how you can specify three dimensional arrays in a list. Sorry. I don't need a psychologist now.


After telling you about two dimensional arrays and how their values can be put in a list. I think a three dimensional array is very clear


Arrays And Lists


There more functions that have to do with lists. But I'm not going to explain them. I just wanted to talk about arrays and lists.


Something Completely Different


Here is something completely different from what you normally read in this blog. It is an imagination.


Imagine this. One day you wake up and you are a millionaire! Look at how different your life will be:


- You no longer have to worry about your debts, bills, and slaving for money.


- You can spend your time doing things you love, spend your time with your beloved family and friends.


- You no longer have to worry about money or have to be poor again. Never again living the life you used to have.


Do you want to be a millionaire? Make your dream lifestyle came true. Here's your chance to be a millionaire. Check this out.


Wake Up Millionaire:
http://l1nk.com/rfbzla



To Your Success


Free AutoLISP Course


Sorry. This offer is only for my readers from Malaysia. I want to give an AutoLISP course to them. Free of charge.


I have more than 900 readers. The majority of them is from the USA. More than 500. But I also have readers from Malaysia. About 120.


I don't know what my readers from Malaysia are doing. Are they with an engineering firm or architecture? Or just interested in AutoLISP?


I offer them a free AutoLISP course. It works like this. You let me know if interested and I'll come to your place.


I will give the AutoLISP course at your office. Your people can attend the AutoLISP course. The course consist of 15 lessons.


The first ten lessons are about AutoLISP. All the functions of AutoLISP are explained and there is talked about the system variables.


During the last five lessons we are going to write an AutoLISP program. The people attending the course come with a wish.


That is why this offer is only for my readers from Malaysia. I live in Malaysia. And I do not see how I could travel abroad.


The AutoLISP course is completely free. I will not charge you for the course. But I will ask you to refund my travel expenses.


The people attending the course will get an e-book about AutoLISP. The e-book is a PDF file. What is said in the course, can be found in the book.