## 1039 Reputation

4 years, 304 days

## It can't be......

The short answer is that generally no, for your matrix B:=Matrix([[a, -b, e], [c, l, d], [-e, -k, m]], simplify command can't  simplify it. Mathematica also can't.

Matrix2.mw

## @Preben Alsholm  Thanks for clarif...

Thanks for clarification.

## ?...

Intial condition: D[1](T)(x, 0) = 0 it's seems to be wrong ?

If I change to D[2](T)(x, 10) = 0(I assume),pdsolve(numeric) give me: Error, (in pdsolve/numeric) unable to handle elliptic PDEs.

## Likely,...

Likely, that means Maple doesn't know a closed-form solution, if it exists.

## ....

"What do you mean by "trivial" corrections?"

I mean for a "trivial": unimportant fixes.

"Do you have an example and do you expect a large jump with 2019?"

I do not have it, and I do not know anything about it.

"Can you provide a list of a few "weaknesses" of int, that are going to be fixed?"

I do not have it, and I do not know anything about it.

English is not my native language,sorry for misunderstanding.

## @digerdiga See Table 1.My opinion P...

See Table 1. and another Table 1 (A very slow progress)

My opinion People from Maple Company are too busy(In introduction of new features,fixing bugs) and do not have time for such trivial corrections in int function.

## No solution....

"Error, (in dsolve/numeric/BVPSolve) matrix is singular" it's probaly means No solution or  infinitely many
solutions.

No_solution.mw

## Possible duplicate...

Almost the same Question here.

## @vv  The question concerned to int...

The question concerned to integral : Int(cos(2*x)/(1+2*sin(3*x)^2), x = 0 .. Pi) not for Int(cos(2*x)/(1+2*sin(3*x)^2), x = 0 .. Pi/2) ? My answer is correct and Maple  returns 0.

```J := Int(convert(cos(2*x)/(1+2*sin(3*x)^2), exp), x = 0 .. Pi); evalf(J) = evalf(value(J));

# 2.065847493*10^(-13) = 0.```

## I'm convinced....

I do not care what the method Maple uses. In this example,Zero is the correct answer.

## Another workaround....

```sol := pdsolve([pde, ic], w(x, t)) assuming t>0,x>0;

#sol := w(x, t) = f(-3*t^2*(1/2)+x)*exp(-t)```

## Workaround....

With no error massages:

`sol := pdsolve([pde, ic], w(x, t), HINT = `*`);`

#sol := w(x, t) = exp(t)*invfourier(fourier(f(x), x, s)*exp(-(1/2)*(3*I)*t^2*s), s, x)

## ....

Thanks for information.

## Quick...

Thanks for quick fix.

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