from gekko import GEKKO
import numpy as np

m = GEKKO(remote=False)

xgrid = np.linspace(-1, 1, 20)
ygrid = xgrid
xg,yg = np.meshgrid(xgrid,ygrid)
z_data = xg*yg

x = m.Var(0.5,-1,1)
y = m.Var(0.5,-1,1)
z = m.Var(2)

m.bspline(x,y,z,xgrid,ygrid,z_data)

m.Minimize(z)

m.solve()