-----maxima-bounces at math.utexas.edu wrote: ----- > (%i3) integrate (integrate (1+sin(5*x*y+y^2), y, -sqrt(1-x^2), sqrt(1-x^2)), x, -1, 1); > defint: lower limit of integration must be real; found -sqrt(1-x^2) This is a bug. Try tracing sign--Maxima fails to recognize that 1-x^2 is pz. --bw