Creating a contour plot with three row vectors

I need to create a contour plot, but my input consists of three row vectors, x_isen, y_isen, and M_isen. At each coordinate of (x_isen,y_isen), I have a value of M_isen. Also M_isen only varies in the x direction so it is constant for all y values at each x coordinate. My y_isen vector is currently all zeros because I am unsure how to make it otherwise even though it should be all y values at each x. My goal is to create a similar plot as I have attached below. Please help!

figure (1)
hold on
grid on
contourf (x_isen,y_isen,M_isen,500,'LineStyle','none')
xlabel('Nozzle Length (m)')
ylabel('Nozzle Height (m)')
title('Mach Value Through Nozzle')

%% Overlay Nozzle Contour
for j=2:n_left_wave
    plot([x(j-1,nwave+1);x(j,nwave+1)],[y(j-1,nwave+1);y(j,nwave+1)],...
        'k','LineWidth',3)
end

% Set some limits on the axes
ylim([0, h_exit*.55]);
xlim([0, length]);
colorbar
colormap('jet')
caxis([1 3])
daspect([1,1,1]);
hold off

Answer 1

[DGM]

I answered a similar question recently.

https://www.mathworks.com/matlabcentral/answers/1693130-how-to-use-a-contour-between-two-curves

The only real difference is that the boundary shape would be straight lines.

% the inputs
x = linspace(0,1,25);
ytop = 0.05 + 0.2*x;
ybot = zeros(size(x));
T = 1 + x*2; % some arbitrary flow data

% plot a patch 
hp = patch([x fliplr(x)],[ybot fliplr(ytop)],[T fliplr(T)]);
hp.EdgeColor = 'none';
hold on; grid on

% plot curves last
axis([0 1 0 0.3]);
plot(x,ytop,'k','linewidth',2);

% add a colorbar
colormap(jet)
hcb = colorbar;

If you want the stepped appearance of a contourf() plot (at least without the lines), you could use a shorter colormap.

If you truly want to do it with contourf(), you'll have to replicate your M vector into a 2D array. This is a similar example showing a truncated pcolor()/contourf() plot

https://www.mathworks.com/matlabcentral/answers/895722-limit-a-contourf-plot-under-a-line