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Stephane Thibodeau (tbodo)
New member
Username: tbodo

Post Number: 1
Registered: 06-2008
Posted on Friday, June 27, 2008 - 06:13 pm:   

Hello,
I'm a beginner in using FlexPDE and I'm not able to find how to use the PI function (Capital Greek pi).
Note: The PI function is the same as "sum" except is a multiplication: PI(var., start, end, expression)
Ex: PI(a,1,5,a^-1) mean multiplication of 1/1 x 1/2 x 1/3 x 1/4 x 1/5 = 1/120!

Another quick question about the "loop"!
I want to create a number of random points in a variable range (as example, one point by unit length). How can I do to fix the density of points INDEPENDENT of the length of that range? If I have a good understand, I can’t use "loop for" with FlexPDE…is it true?

Thanks!

T-bodo
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Robert G. Nelson (rgnelson)
Moderator
Username: rgnelson

Post Number: 1145
Registered: 06-2003
Posted on Friday, June 27, 2008 - 07:48 pm:   

1.
FlexPDE doesn't implement a PI (product) function. You'll have to use an EXP of a SUM of LN'S.

2.
FlexPDE doesn't have a LOOP statement.
There is a REPEAT ... ENDREPEAT capability, which is a textual repeat. See "Repeat" in the Help Index.

3.
You can use the RANDOM(arg) function to generate a random number uniform in (0,arg).
FIXED POINT(RANDOM(2),RANDOM(2))
for example, will generate a gridding point somewhere in the square (0,2)(0,2).

You can do arithmetic on random numbers to create variables with non-uniform probability density. See textbooks on probability theory or Monte Carlo methods.

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