interp1 issue - resampling

variable1=[24.6944086885135;21.0998152063394;14.7533601994682;6.76823133654033;6.73000233602188;8.34930121372767;29.2864760248330;43.5413625307145;46.7782562150740;48.3839944347439];

auxvariable2=linspace(1.1,156.3,1569); 

output=interp1(variable1(1:10,1),auxvariable2);
%

Hi. I got a question about interp1.

I have the data from variable1. I want to create 1569 new points using that data.

I don;t know the function, so I am using interp with 2 parameters.

I am expecting to get 1569 points, but I get 90 points and the rest until 1569 are NaN.

What am I getting wrong?

Thank you!

Answer 1

[Star Strider]

Try something like this —

variable1=[24.6944086885135;21.0998152063394;14.7533601994682;6.76823133654033;6.73000233602188;8.34930121372767;29.2864760248330;43.5413625307145;46.7782562150740;48.3839944347439];
v1 = 1:numel(variable1);
v2 = linspace(min(v1), max(v1), 1569);
output = interp1(v1, variable1, v2).';

szvariable1 = size(variable1)

szvariable1 = 1×2

10 1

szoutput = size(output)

szoutput = 1×2

1569 1

figure
plot(v1, variable1, '.b', 'MarkerSize',10, 'DisplayName','Original')
hold on
plot(v2, output, '.r', 'MarkerSize',0.1, 'DisplayName','Interpolated')
hold off
grid
legend('Location','best')

figure
plot(v1, variable1, '.b', 'MarkerSize',10, 'DisplayName','Original')
hold on
plot(v2, output, '.r', 'MarkerSize',0.5, 'DisplayName','Interpolated')
hold off
grid
legend('Location','best')
xlim([4.75 5.25])

EDIT — (4 Nov 2022 at 16:38)

Added second plot for clarity.

.

[Andra Topan]

Brilliant! Thank you so much!

[Star Strider]

As always, my pleasure!