interp1 result not close to sampled curve with rather simple data

Hello everyone,

might be a simple question, I am using the interp1 function to resample a curve but the resulting curve is not even close to the input data:

Brownish one is the input curve, yellow/blue are the Results for Makima or linear interpolation. Here is the an mwe code with the used Data:

%% x values of the curve
x = [0.0127	0.0168	0.0279	0.0409	0.0561	0.0717	0.0863	0.0995	0.1103	0.1185	0.1250];
%% y values of the curve
y = [0	0.0247	0.0528	0.0784	0.1047	0.1280	0.1491	0.1637	0.1732	0.1787	0.1816];
%% sampling interval
interval = [0	0.0090	0.0181	0.0272	0.0363	0.0454	0.0545	0.0636	0.0727	0.0817	0.0951	0.1102 ...	
    0.1250	0.1392	0.1517	0.1620	0.1698	0.1752	0.1788	0.1816];
%% Resampling at interval points
x_val_sampled = interp1(y,x,interval,'makima');
plot(x,y,x_val_sampled(1:10),x_val_sampled(11:20))

Probably something small I am missing but I cant seem to figure it out by myself. Thanks for your time!

Answer 1

[Star Strider]

The plot call is wrong.

It should be something like:

plot(x,y, x_val_sampled(11:20), interval(11:20))

Try this —

%% x values of the curve
x = [0.0127	0.0168	0.0279	0.0409	0.0561	0.0717	0.0863	0.0995	0.1103	0.1185	0.1250];
%% y values of the curve
y = [0	0.0247	0.0528	0.0784	0.1047	0.1280	0.1491	0.1637	0.1732	0.1787	0.1816];
%% sampling interval
interval = [0	0.0090	0.0181	0.0272	0.0363	0.0454	0.0545	0.0636	0.0727	0.0817	0.0951	0.1102 ...	
    0.1250	0.1392	0.1517	0.1620	0.1698	0.1752	0.1788	0.1816];
%% Resampling at interval points
x_val_sampled = interp1(y,x,interval,'makima');
plot(x,y, x_val_sampled(11:20), interval(11:20),'p-')

.