def integral(self, xa, xb, ya, yb):
tx,ty,c = self.tck[:<NUM_LIT:3>]<EOL>kx,ky = self.degrees<EOL>return dfitpack.dblint(tx,ty,c,kx,ky,xa,xb,ya,yb)<EOL>
Evaluate the integral of the spline over area [xa,xb] x [ya,yb].

Parameters
----------
xa, xb : float
    The end-points of the x integration interval.
ya, yb : float
    The end-points of the y integration interval.

Returns
-------
integ : float
    The value of the resulting integral.