can anyone explain this: sage: integrate(legendre_P(64,x)sin((1+x)pi/2),x,-1,1).n() 1.16508247725542e79
from approximation one know's that the legendre coefficients converge exponentially to zero and not to infinity!
and indeed with mpmath I get a better answer: sage: import sage.libs.mpmath.all as mpmath sage: mpmath.call(mpmath.quad,lambda x: mpmath.legendre(64,x)mpmath.sin(pi/2(x+1)),[-1,1]) -5.04684703543649e-25
Is there an overhead happening, when I numerically evaluate large rationals or something???
Thanks in advance, maldun