## Auto- and cross-correlation with Maple...

How do I perform auto- and cross-correlations in Maple?

## Sorting through multiple solutions...

My students are sometimes asked to use Maple commands that give multiple answers (solve and dsolve, most commonly) and then are asked to select a certain solution out of those returned. E.G. dsolve(diff(y(x),x) = 1/2*(6*x^3+2*sin(8*x)^2)/(y(x)^2)); returns 1 real solution and 2 complex solutions. The students are asked to select the real solution and assign it to a variable. I have making sure that Maple will select the correct solution out of the set (or list or sequence) for me by using complicated if statements. E.G. The first part of the if statement I use for the dsolve() command above is if evalf[50](subs({x=1,_C1=1},Re(rhs(solsde[1])))) =evalf[50](subs({x=1,_C1=1},rhs(solsde[1]))) then real_solution:=rhs(solsde[1]); fi; I leave off the two elif parts after the first if ... then for the sake of brevity.

## and...

how do i incorporate an and clause for my if statement? like if a=1 and b<>3 then

## how do i output text?...

i want to output text. if n=b then; n may not be completely factored end if; how do i do this?

## Plotting the Dirac Function...

Hi there everyone. I have recently been trying to plot fourier transforms. After taking the fourier transform of a particular function of the time domain for example a sinusoid. I get a sum of terms each with a translated Dirac function. When I try and plot the series of Dirac functions it doesnt work in the sense that there is nothing displayed. The plot initializes but there are no Dirac functions. Is there a way to plot Dirac Functions? thanks

## interpolation or approximation with two variables...

Dear Maple Users, I have the following problem: How to find the best-fitted function P(x,y) = ax+by+cxy+d to the following data: i= 0, 1, 2, 3, 4 , 5 , 6 , 7 xi= 150, 152, 154, 156, 156, 157, 158, 158 yi= 134, 136, 106, 61, 90, 124, 41, 135 I know that in Maple functions that can solve interpolation and approximation problems with one variable are implemented. But how to solve the problem with two variables? Best regards, Wieslaw Kotarski kotarski@gate.math.us.edu.pl

## loops...

if i have a procedure that has a bunch of loops, but when i execute it seems to be taking a long time. is there a way to figure out which loop the procedure is 'stuck' in?

## does not command...

what's the does not command for a for loop? as in for i from 1 to 100 while i (does not) equal 5.

## HELP ME...

Hi to everybody I'm a new user of Maple How can I solve this system? > eq1:=1039.44*Diff(Diff(ck(r),r),r)+80960*Diff(ck(r),r)*Diff(p(r),r)+80960*ck(r)*Diff(Diff(p(r),r),r)=0; / 2 \ | d | / d \ / d \ eq1 := 1039.44 |---- ck(r)| + 80960 |--- ck(r)| |--- p(r)| | 2 | \ dr / \ dr / \ dr / / 2 \ | d | + 80960 ck(r) |---- p(r)| = 0

## Chat...

Is there a chat or instant message capability on this website ?

## Help with the final procedure at the end of this w...

Can anyone discover the reason for the troubles i'm having with the last execution group ? I think the few ones above it are some previous attempts. it's the part that begins as >Cardioid := proc(S) local s; etc... > Warning, the name changecoords has been redefined >

## ploting...

i have this code: S := []; for i from 0 by 5 to 150 do S:=[op(S),[i,(i+3)^2 mod 7]]; end do; plot(S, style = point) i want to plot points connected by lines. how do i do this?