## 12685 Reputation

8 years, 264 days

## int - too many levels of recursion...

Maple 2018

A simple (?)  int and too many levels of recursion

 > J := Int(cos(2*x)/(1+2*sin(3*x)^2), x = 0 .. Pi);
 (1)
 > evalf[30](J);
 (2)
 > value(J);
 >

The workaround I know (for J = 0) it is not very simple.
Can you find an easy one?

Maple 2018

Executing the entire worksheet several times I obtain random results for Threads:-Seq

 > restart;
 > N:=10^3; f:= (a,b) -> add(evalf(j), j=a..b);
 (1)
 > seq(f(k*N/4+1,(k+1)*N/4), k=0..3);
 (2)
 (3)
 (4)
 (5)
 >

## Forum activity ...

MaplePrimes

It seems that the forum activity of the user     is no longer accessible.
Is it a site problem?

## isolve and _SolutionsMayBeLost...

Maple
 > sys:={x+y=10,x^2-y^2+z^2=1};
 (1)
 > isolve(sys, n);
 (2)
 > _SolutionsMayBeLost;  # It was set in Maple 10 or so!  E.g. x=5,y=5,z=-1 is not found.
 (3)
 > # Workaround
 > yz:=eliminate(sys,x);
 (4)
 > S:=isolve(yz[2], n);
 (5)
 > map(u -> ( u union eval(yz[1],u) ), [S])[];  # The correct solution
 (6)
 >

Maple

 > restart;
 > with(IntegrationTools):
 > # A very simple double integral
 > J:=Int(Int(x^2, x = 0 .. y), y = 0 .. 1);
 (1)
 > value(J);
 (2)
 > # Try a simple change of variables
 > Change(J, x=t*y, [t]);   # Why this form?
 (3)
 > value(%);
 (4)
 > # Now the same for 2*J
 > Change(2*J, x=t*y, [t]);  # OK, but why?
 (5)
 > value(%);
 (6)
 >
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