The function contour has different outputs in Scilab than in MATLAB?

Question

I'm trying to convert this Matlab code to Scilab, but I have some problems.

clear all; clc;
c0  =  0.8;
c1  =  1.3;
c11 = -6.1;
c12 = -0.6;
c2  =  1.7;
c22 = -1.7;
g = 0.05; 
d = 0.01; 
x1 = -9; 
x2 = 8; 
k = 1;  
kmax = 100; 
x1trace = [x1]; 
x2trace = [x2]; 
i = 2;

while k < kmax 
    gr1 = c1 + c12*x2 + 2*c11*x1; 
    x1 = x1 + g*gr1
    x1trace(i) = x1; 
    x2trace(i) = x2;
    i = i + 1; 
    gr2 = c2 + c12*x1 + 2*c22*x2; 
    x2 = x2 + g*gr2
    x1trace(i) = x1; 
    x2trace(i) = x2; 
    i = i + 1; 
    if sqrt(gr1^2 + gr2^2) <= d; 
        break; 
    end
    k = k + 1; 
end

x = -10:0.1:10; 
y = -10:0.1:10; 
[X, Y] = meshgrid(x, y); 
Z = c0 + c1*X + c2*Y + c12*X.*Y + c11*X.^2 + c22*Y.^2; 
[C, h] = contour(X, Y, Z); 
clabel(C, h); 

hold on;
plot(x1trace, x2trace, '-'); 
text(x1trace(1) + 0.2, x2trace(1) + 0.5, 'M0'); 
text(x1 + 2, x2, ...
strvcat(['x1 = ' (num2str(x1))], ...
        ['x2 = ' (num2str(x2))], ...
        ['k = '  (num2str(k))])); 
hold off;

I get an error for this line:

[C, h] = contour(X, Y, Z);
Wrong number of output arguments.

What should I change to fix it? Are there also any other errors in the code ?