## 1285 Reputation

4 years, 286 days

## strange old rand() behavior in Maple...

Maple

http://www.maplesoft.com/applications/view.aspx?SID=1526&view=html

near the middle, it says

I just tried in Maple 2016 and that is not what it did. It says this was in Maple 8. It seems this was "fixed" in Maple 2015.

My question: How could Maple 8 have simplified rand()/rand() to 1 before evaluating rand()?  i.e. why was not rand() evaluated first, before the simplification was made? it seems to have worked as if one typed x/x , but rand() would have been a function, and it should be evaluated before?

Just wondering why Maple 8 did the above, that is all.

## can Maple find solution to eigenvalue bo...

Maple

newbie here. When I give Maple 2016.2  a boundary value ODE with an eigenvalue in it, it returns the trivial solution. I was wondering if Maple supports finding non-trivial solution and also give the eigenvalue values associated with the non-trivial solution?

restart;
ode:=diff(y(x),x\$2)+lambda*y(x)=0;
bc:=y(0)=0,y(L)=0:
assume(L>0,L,'real'):
sol:=dsolve({ode,bc},y(x));


The outtput is y(x)=0

In Mathematica, it gives both trivial and non-trivial solution:

Clear[L0, lam, x, y, r]
ode = y''[x] + lam y[x] == 0;
bc = {y[0] == 0, y[L0] == 0};
sol = Assuming[Element[L0, Reals] && L0 > 0,
DSolveValue[{ode, bc}, y[x], x]]

If Maple does not currently support this, any one knows if this will added to Maple 2017?

## does Maple have build-in support to gene...

Maple

I googled and not able to find something. But may be it is inside some package which google do not show. I am looking for build-in command in Maple (or external package is OK) to generate Green function for ODE's and PDE's similar to Mathematica's https://reference.wolfram.com/language/ref/GreenFunction.html

When I do ?Green in the worksheet, I see only definitions and help on the color Green. But nothing about actual command relating to Green function.

I find this surprising, given that Maple main strength is in the domain of differential equations.

If not allready there, anyone knows if this will be in Maple 2017?

## is it possible to capture output of dism...

Maple

Is it possible to capture and convert the output of dismantle to one (long) string?

For example, if I do

r:=dismantle(x+sin(x));

SUM(5)
NAME(4): x
INTPOS(2): 1
FUNCTION(3)
NAME(4): sin #[protected, _syslib]
EXPSEQ(2)
NAME(4): x
INTPOS(2): 1

I'd like to first capture the output in "r", which now it does not, it just goes to screen and "r" is left empty, and then convert the result to long string. (using convert()) So the result of the above will becomes

r:="SUM(5) NAME(4): x INTPOS(2): 1 FUNCTION(3) NAME(4): sin #[protected, _syslib]..."

The reason I need to capture the output, is so I can more easily look for some specific name/content inside the expression. which is now in a string, using string tools later on, which I think will be easier. For example, if I want to look for "sin" I can now search the above string and see if "sin" is there. Context is not important, just need to see if a name happens to be in the string.  The problem I do not know how to convert output of dismantle to string.

Maple 2016.2 on windows

## How to make ExportMatrix not escape stri...

Maple ended up corrupting all my files.

I did

data:=ImportMatrix("foo.txt", source=csv);
ExportMatrix("foo.txt",data,target=csv);

Expecting the same file not to change.  But on input the file was like this

1,2,3,4,0.1,5,"int(x^2,x)","\frac{x^3}{3}",6,7,"(2*x + 1)^(3/2)/3","A"
1,2,3,4,0.1,5,"\cos(x)","\sin(x)",6,7,"(2*x + 1)^(3/2)/3","A"

After ExportMatrix the file because like this

1,2,3,4,.1,5,"int(x^2,x)","\\frac{x^3}{3}",6,7,"(2*x + 1)^(3/2)/3","A"
1,2,3,4,.1,5,"\\cos(x)","\\sin(x)",6,7,"(2*x + 1)^(3/2)/3","A"

It added an extra "\" each time it saw "\" in the string. I did not want it to do this. This ended up corrupting all my Latex code, which means I have to recreate all the files now. (did not notice this first time I tested it). So each time I run this code, this file becomes

1,2,3,4,.1,5,"int(x^2,x)","\\\\\\\\\frac{x^3}{3}",6,7,"(2*x + 1)^(3/2)/3","A"
1,2,3,4,.1,5,"\\\\\\\\cos(x)","\\\\\\\\\sin(x)",6,7,"(2*x + 1)^(3/2)/3","A"

and so on.

I looked at all options, and so far, not able to see option to tell it not to do this. With so many options I am not sure what to try now.

Any one knows how to tell ExportMatrix not to add "\" ?  Maple 2016.2

I simply wanted to read the file, and make one change in field, and write the file back to same format it was.

 1 2 3 4 5 6 7 Last Page 1 of 31
﻿