Can't figure out the error in my pcolor line, keep getting color data input must be a matrix error

xvalues =[-15.0:0.25:15.0]';
gvalues = gzx(xvalues,p,z);  %evaluates xvalues for a defined function for a constant p & z (function is defined later in the code)
Xdata = [xvalues, gvalues];
XLB = [3.5; 7500]
XUB = [7.0; 12500]

%... Calculate grid to plot hump function
opt=0;
DX1=0.03;
DX2=10;
[x1, x2] = meshgrid(XLB(1):DX1:XUB(1),XLB(2):DX2:XUB(2));
[M0,N0]=size(x1);
xx1=x1(:);
xx2=x2(:);
n=size(xx1,1);
for ii=1:n
    fplot(ii)=costfunct([xx1(ii);xx2(ii)],Xdata);
end
fplot=reshape(fplot,M0,N0);

%plot
hf = figure();
colormap jet;
pcolor(x1,x2,fplot);
shading interp
hold on

[Walter Roberson]

We do not know XUB or XLB

[Tyler Stephen Kuehn]

Sorry forgot to include those bits, I had defined XLB and XUB

Answer 1

[Steven Lord]

Please run this command immediately before the line where you call pcolor and show us the output from just before the pcolor call that throws the error.

whos x1 x2 fplot

My suspicion is that fplot was initialized to something that's not numeric (like a sym array) and can't be converted into a double array in order to be used in pcolor, something like x in the example below.

x = sym('x', [10 10]);
pcolor(1:10, 1:10, x)

[Tyler Stephen Kuehn]

Name         Size              Bytes  Class     Attributes

  fplot      161x117            150696  double              
  x1         161x117            150696  double              
  x2         161x117            150696  double 
  
  

for some reason when I put the whos command in there and change nothing else it now works, and the plot is showing up as expected. Not sure why but Thanks!