x,y=var('x,y')
w=x*x-y*y
w1=diff(w,x,2)
w2=diff(w,y,2)
w3=w1+w2
a=integrate(w3,(x,0,1))
p=integrate(a,(y,0,1))

Kreyszig-9.4-4 (last edited 2010-12-16 11:28:04 by 172)