## 380 Reputation

10 years, 248 days

## Problem in IntegrationTools:-Change ?...

Maple 2019

Just wanted to ask, what the issue here is:

restart;
Int(1/(1 - x*ln(x)), x);
IntegrationTools:-Change(%,u=1-x*ln(x),u);

doesn't give the proper transformation. It gives

Int(1/u,u)

Solving for x and writing the transformation in terms of LambertW gives something else, if I'm not mistaken.

## assuming x::constant doesn't work with D...

Maple 2019

Hello,

I have this simple problem which doesn't want to work.

restart;
d := g -> (D@@2)(g) - x^2*g;
((d@@2)(g) assuming x::constant);

The result of the last line is:

(D@@4)(g) - 2*(D@@2)(x)*x*g - 2*D(x)^2*g - 4*D(x)*x*D(g) - x^2*(D@@2)(g) - x^2*((D@@2)(g) - x^2*g)

so Maple doesn't set D(x) to 0. On the other hand if I just write

D(x) assuming x::constant

then Mapel returns 0.

Similarly

D(f^k) assuming k::constant

just returns D(f^k) and not k*D(f)*f^(k-1) as the example in HELP suggests.

## Wrong integral result...

Maple 2019

Hello, There seems to be a bug in the int() routine when CPV is being used i.e.

restart;
f1 := (int(t^(2*a - 1)/(-t^2 + 1), t = 0 .. infinity, CPV = true) assuming (0 < a, a < 1));

the result given is

f1 := Pi/(2*sin(Pi*a)*(-1)^(1 - a))

but the correct result is

f1 := Pi/2*cot(Pi*a).

Maple 2019

Hello, I was wondering about the following.

cos(Pi/2^n) can be converted to a radical for each integer n, because cos(Pi/2)=0 is known and successively

cos(x)=sqrt( (1+cos(2x))/2 )

so in principle radical expressions should exist for all integers n. But maple only converts cos(Pi/8) to a radical, but not cos(Pi/16) and higher powers. Is there a simple way without writing an own program to obtain these radical expressions using convert(*,radical)?

## Physics Commutator does not sum over rep...

Maple 2019

Hello,

 >
 (1)
 >

I have the following issue.

The way it is set at the moment, works kinda in that the final result is 0, which I tried to check.

However, the expression L2L2X[1] is not fully Simplified, since the term

-(4*X[a])*X[b]^2*P[a]*P[k] + (4*X[b]^2)*X[f]*P[f]*P[k]

is actually zero. I suppose that he doesn't manage because of the different indices "a" and "f" here. How can this be fixed?

When I comment out "Define" and use "Coordinates(X,P)" instead, it doesn't work. Seems to give the wrong result (Difference is not zero).

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