Could anyone comment on the convexity of f(x,y) = (x^2) * exp(y) ...... i.e. x square into e to the power y. I did try to find Hessian of the same and the value I get is : Hessian(x,y) = -2 * x^2 * exp(2y).... which looks <= 0 for all x and y. I assume this should imply f(x,y) is concave. However when I plot this function using a 3D graph plotter it seems convex . try hp://ww.livephysics.com/ptools/online-3d-function-grapher.php for plotting function. I am sure I am making a simple mistake or something. Any help would be useful.