“Error, too many levels of recursion” ,but there’s just a single expression.

How can this happen?

I am using Maple 15 to numerically solve a system of differential algebraic euqations (DAE) with given initial conditions, and I've tried rfk45_dae and rosenbrock_dae solver, but both solver responded in error like this

Error, (in dsolve/numeric) cannot numerically solve complex DAE initial value problems, the system must be converted to a real system

I don't understand what is a real system, and how could i convert it to a real system.

I'm running a long loop with a lot of variables. I have noticed that Maple does not seem to clear its memory after each loop iteration, which results in very large memory used after all the iterations. I can't use restart because I need a few variables to be remembered throughout the loop for analysis afterwards. So the question is how to clear the memory for selective variables and procedures at the end of each iteration.

How to make a usual book view of a system of equations? I want that each equations is placed on new line with curly brace on the left.

I need to plot a function:



f(1.0) gives a correct result but plot doesn't. Could you help me with it?

Dear those who are in Mapleprimes,

As I can't understand how Maple calculate the quick sort, I write the present question, hoping that someone give me a hint.

In essence, nested procedure I cannot understand is this:

quicksort:=proc(A,m,n)

....................

if m<n then

quicksort(A,m,p-1);.................................(1)

quicksort(A,p+1,n)...................................(2) 

end if;

eval(A);

end proc:

Details were ommitted, but I have to say that p is the number between m and n, which is determined by ommitted parts of 

the procedure.

And, with this nested procedure, 

quicksort([2,4,1,5,3],1,5) is calculated.

What I want to know is how to process the parts of (1) and (2).

If after (1) is processed, (2) is processed, what is the value of p in (2).

Is it the p which is determined successively through processing nested value of (1)?

Thank you in advance.

taro

Can anyone help to compute the following integral in terms of the bessel functions in maple.

Hey guys! Can someone please help me by telling what I can insert into maple to get answer for this question? Thanks!

Please I want to know how to solve this integration.

int(exp(-(ln(y)-2*sigma^2)^2/(8*sigma^2))/(y*sqrt(8*Pi*sigma^2))*exp(-(ln(y+z)-2*sigma^2)^2/(8*sigma^2))/((y+z)*sqrt(8*Pi*sigma^2)), y = 0 .. infinity)

The help documents read，

“

 The function unames returns an expression sequence consisting of all the active names in the current Maple session which are ``unassigned names''.

“

But what unames() returns is obviously not the contents one expects:

i am trying to execute the following code but i am having the following error:

A:=Matrix(21,4):A(1,2):=0:A(2,2):=0:t:=2: thetasec:=-8.724679300*10^(20):  for z from 0.1 by 0.05 to 1 do  t:=t+1: A[t,1]:=z:  x:=2*A[t-1,2]-A[t-2,2]+thetasec*0.05^(2):  theta2:=evalf(arctan(sin(x-Pi),cos(x-Pi))+Pi):    if theta2>Pi/(2)and theta2<=(3*Pi)/(2)then   A[t,2]:=theta2-Pi   elif theta2>(3*Pi)/(2)then A[t,2]:=theta2-2*Pi else  A[t,2]:=theta2 fi:  A[t,3]:=cos(A[t,2]):  A[t,4]:=sin(A[t,2]):od

Error, cannot determine if this expression is true or false: (1/2)*Pi < 3.535344555 and 3.535344555 <= (3/2)*Pi

what is causing this error and how can i fix it 

I'm using Maple 12 to solve a system of differential equations numerically. I first define my system as "sys1" and then use the command:

sol1 := dsolve(sys1, numeric, output = listprocedure, range = 0 .. 2000)

I'm using output=listprocedure because that's what the Maple's Help says if I want to use individual solutions. So my differential equation system has 8 solutions, and I label them a1(t) through a8(t). Now after solving the system I want to be able to evaluate, e.g., a1(t) at t=100.

I then follow the Maple's Help by defining:

f1(t):=eval(a1(t),sol1)

But then if I do:

f1(100)

I don't get the expected numerical value. Instead I get a1(100) as the result.

What I managed to do however was to plot f1(t) with the following command:

plot(f1(t),0..2000)

So it seems that I did it partially right. However according to the Maple's Help I should be able to extract numerical values with f1(100). 

I'd appreciate any suggestions!

Hello,

It is not a very important question... but i like when i have a nice worksheet.

I would like to change the color of the maple input. Unfortunately, i manage to change the color for the inputs already created but not for the new maple input.

How can i change the color for the new maple input i want to create ?

Thank you for your help.

I saw the expression:

proc(a::array(1, mumeric))

the decration of a is array(a, numeric).

But, I can't find still now the expression of array(a, numeric) in HELP in maple.

In the term of array, it is written that it takes as arguments indexfcn, bounds, list.

as in  array( indexfcn, bounds, list).

1 in array(1, mumeric)) is bounds, and probably numeric in array might mean each terms of the array such as (1,2,3)

has to take the property of being numeric. But, it is not written in the term of array in the HELP of Maple.

Where can I find that syntax of array of array(1, numeric)?

Thanks in advance.

taro 

How can I solve raychaudhuri equations numerically using GRtensor?