function g = wood_gradient(x1, x2, x3, x4)
##
- ## The gradient of the Wood function. See wood.m for more information.
+ ## The gradient of the Wood function. See wood.m for more
+ ## information.
##
f_x1 = 400*(x1^2 - x2)*x1 + 2*x1 - 2;
f_x2 = -200*x1^2 + 220.2*x2 + 19.8*x4 - 40;