# Limit a CONTOURF plot under a line

4 views (last 30 days)
Andrea Palmarini on 10 Aug 2021
Answered: DGM on 11 Aug 2021
Hi,
I want to limit the contour plot of u under the black curve h wich is a function of x: h=h(x). Indeed, u is a function of x and h: u=u(x,h). How may I do it? Thanks in advance for your help. Until now, I wrote the following code:
yyaxis left
plot(x,B)
xlabel("dimensional streamwise")
ylabel("magnetic field")
yyaxis right
plot(x,h)
ylabel("dimensional interface")
grid on
hold on
[X,Y]= meshgrid(x,h);
U=ones(1000).*u;
contourf(X,Y,U,'edgecolor','none')
hold on
colorbar
% dimensions of the variables
% x 1000x1
% B 1000x1
% h 1000x1
% u 1000x1
% U 1000x1000
Regards,
Andrea DGM on 11 Aug 2021
Consider:
numpoints = [1000 1000]; % [x y]
% build boundary curve
x = linspace(-2,2,numpoints(1));
y = 4*x-x.^3;
% build 2D map
y2 = linspace(-4,4,numpoints(2)).';
z = sin(x*2).*sin(y2*2);
% set unwanted map data to NaN
z(y2>y) = NaN;
% pcolor is probably what you're after
pcolor(x,y2,z)
% or you could use contourf if that's really what you want
%contourf(x,y2,z,'edgecolor','none')
hold on
% using a thick line helps hide the ragged edge
h = plot(x,y,'k','linewidth',3);
colormap(summer) R2021a

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