I believe what you want is Reverse —
x = linspace(0, 1);
y = exp(-(x-0.5).^2*50);
figure
plot(x, y)
grid
figure
plot(x, y)
grid
Ax = gca;
Ax.YDir = 'Reverse';
EDIT —
EDIT — (10 Sep 2023 at 10:33)
Applying that here —
clear, clc, close all
%number and location of seismometer depths (change n to 4 for the part (e)).
n=100;
%n=4;
z=linspace(0,20,n+1)';
z=z(2:end);
Deltaz=z(2)-z(1);
%velocity gradient
g=40;
%velocity at z=0;
v0=1000;
%true velocity at midpoints
v=v0+(z-Deltaz/2)*g;
%true slowness
s=1./v;
%perfect data (analytic solution)
t=(1/g)*(log(v0+z*g)-log(v0));
%G matrix
G=tril(ones(n,n))*Deltaz;
figure(1)
plot(z,t,'k',z,G*s,'r-.')
Ax = gca;
Ax.YDir = 'Reverse';
xlabel('Depth (m)')
ylabel('Travel Time (s)')
legend('Analytical','Discretized','location','southeast')
figure(2)
plot(z,s,'k',z,G\t,'r-.')
Ax = gca;
Ax.YDir = 'Reverse';
xlabel('Depth (m)')
ylabel('Slowness (m/s)')
legend('m_{true}’,’m')
title('Noise-free Solution')
%add noise to the travel time data vector
tn=t+0.00005*randn(size(t));
figure(3)
plot(z,s,'k',z,G\tn,'r-.')
Ax = gca;
Ax.YDir = 'Reverse';
xlabel('Depth (m)')
ylabel('Slowness (m/s)')
legend('m_{true}’,’m')
title('Noisy Solution')
.
