# Question:Maple does not integrate when I use "for...do" loops

## Question:Maple does not integrate when I use "for...do" loops

Maple
Hi, I am trying to evaluate a number of N[i,j] variables and part of the process of finding them includes "Int" and afterwards "evalf". In case I calculate them manually as in (functions, variables and constants previously defined): G11 := diff(psi2, a[1], a[1]); dpsi2 := diff(psir2, a[1], a[1])+diff(psiz2, a[1], a[1]); Izr := -E*(Int(u*G11, [z = -infinity .. infinity, r = 0 .. infinity]))+Int(u*((j*g0+j^2/r^2+(1/4)*g0^2*r^2-2/rho)*G11+dpsi2), [z = -infinity .. infinity, r = 0 .. infinity]): Izr2 := evalf(Izr); N[1,1] := (a[1]*a[1])*Izr2; I obtain neat results for Izr2 and N[1,1] (i.e. the integration is done and results in a number). However, in case I use "for... do" loops, the integration is not performed. Something like (same functions, variables and constants as before): for i from 0 to 1 do for j from i to 1 do Gij := diff(psi2, a[i], a[j]): dpsi2 := diff(psir2, a[i], a[j]) + diff(psiz2, a[i], a[j]): Izr := -E*( Int( u*Gij, [z=-infinity..infinity, r=0..infinity] ) ) + ( Int( u*((j*g0+j^2/r^2+g0^2*r^2/4-2/rho)*Gij+dpsi2), [z=-infinity..infinity, r=0..infinity] ) ): Izr2 := evalf( Izr ); N[i,j] := a[i]*a[j]*Izr2; end do; end do; In this case Izr2 and N[1,1] are not neat since the definite integrals are displayed, hence not they were not evaluated (although Maple spends some time trying to). Could anyone please tell me which mistake I am making in my loops?
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