nm

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13 years, 25 days

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These are questions asked by nm

restart;
ode:=diff(y(x), x, x)-y(x)*(a^2*x^(2*n)-1);
dsolve(ode,y(x));

gives

     DESol({diff(_Y(x), x, x)+(-a^2*x^(2*n)+1)*_Y(x)}, {_Y(x)})

as answer. I read the help on DESol, but what does the above actually mean? Where is the solution of the ode? It just returned the ode back to me. Can I consider that Maple did not solve this ode in this case?

from help

"DESol is a data structure to represent the solution of a differential equation. It is to dsolve as RootOf is to solve."

 

 

I'd like to try the new Maple IDE

http://www.maplesoft.com/products/toolboxes/IDE/index.aspx

Maple IDE - Integrated Development Environment

Is there a way to obtain a trial version even for a week just to try it out? I do not want to spend all this money then find out it does not work well.

any one here uses this and can recommend it or comment on how well it works? For example, can one run Maple code directly from it and have the code execute in Maple, or must one load the file manually from the editor into Maple to run it each time they make any changes to the code?

restart;
k:=1;
sum(k^2,k=1..10);
      (in sum) summation variable previously assigned, second argument

gives an error, since k is not free. Fine. No problem. But add() has no problem with an assigned variable:

restart;
k:=1;
add(k^2,k=1..10);

and seq() has no problem either

restart;
k:=1;
seq(k^2,k=1..10);

It is confusing when learning Maple since it does not seem to behave the same way in all its functions. What is the reason for this design? 

Hello.

Two related questions: I'd like to measure the CPU time used by a computation. Should I use with(CodeTools)? or use  time[real]? What would be the most accurate way to measure the CPU time used by one call, say dsolve()?

Also, How would one return both the result of the computation and the time used in one call so that one does not have to make two separate calls: to obtain the result and to obtain the CPU time?

Example:

restart;
with(CodeTools):
ode:=2*a*x^3*y(x)^3+2*x*y(x)+diff(y(x), x);
result:=Usage(dsolve(ode=0,y(x)),output='cputime');

Gives result:=0.141 while

restart;
ode:=2*a*x^3*y(x)^3+2*x*y(x)+diff(y(x), x);
result:=time[real](dsolve(ode=0,y(x)));

Gives result:= 0.145

But in both cases, I have to make another call to get the result of the DSolve in this example. result:=dsolve(ode=0,y(x)); which I'd like to avoid if possible. 

I am using Maple 18

 

restart;
eq:=diff(y(x),x) - y(x)^2 - x*y(x) - x + 1;
r:=dsolve(eq,y(x));
latex(r);

Gives an error "(in fprintf) string expected for string format". The problem seems when the math contains "erf"? Both examples below fail with result that contains this.

Maple 18, on windows 7.

Another example:

restart;
eq:=diff(y(x),x) + a*y(x)*(y(x)-x) - 1;
r:=dsolve(eq,y(x));
latex(r);

Another example, which seems to fail for different reason

restart;
eq:=diff(y(x),x) + a*x*y(x)^3+b*y(x)^2;
r:=dsolve(eq,y(x));
latex(r);

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