How to use a contour between two curves?

I have a nozzle profile and I wish to colour the nozzle using contours. But my colouring appears outside the nozzle area.

x=linspace(0,3,31);

a=1+2.2(x-1.5)^2;

now, I have a 1D temperature array(1 x n) that I wish to express between the two curves as shown below

figure(1)

subplot(3,1,1)

axis([0 3 0 6]);

plot(x,a,'r');

hold on

plot(x,-a,'r');

Kindly help.

Answer 1

[DGM]

You can use a patch object, but you'll have to specify the colormapping. This should be fairly straightforward, as your vertices are uniformly spaced along x.

% the inputs
x = linspace(0,3,31);

y1 = 1 + 2.2*(x-1.5).^2;
y2 = -y1;

T = -cos(x/3*pi); % some arbitrary temp data

% plot a patch 
patch([x fliplr(x)],[y2 fliplr(y1)],[T fliplr(T)]);
hold on
colormap(parula)

% plot curves last
axis([0 3 -6 6]);
plot(x,y1,'r');
plot(x,y2,'r');

% add a colorbar
hcb = colorbar;

In this case, T is being used essentially as color data. The relative values in T (with respect to the extrema of T) correspond to the position within the colormap.

Answer 2

[Image Analyst]

See the FAQ:

https://matlab.fandom.com/wiki/FAQ#How_do_I_shade_the_region_between_two_curves.3F

[praveen sundararajan]

Not working. Can you provide any other alternative?

[Image Analyst]

Let's see your code where you attempted to implement the FAQ method. You forgot to attach it for some reason.

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