var('x,y')
f=function('f',x,y)
f=2*x**2+4*x*y+y**2;f
F=diff(f,x);F
F(1,-1)
print "f and F  are not positive definite"

Strang-6.1-2 (last edited 2010-12-18 10:43:44 by sarada)