Here is a quick example of linear interpolation.

%% Linear Interpolation Example

% James Eastham, Member IEEE

% 10/15/2012

close all;

clear all;

x = 0:100; %Original Data Points

y = sin(x); % sin of original data points

xi = 0:.5:100; % points to interpolate

yi = interp1(x,y,xi); % interpolated vector

figure('Color',[1 1 1]);

subplot(3,1,1);

plot(x,y,'o-g',xi,yi,'.-b')

title('Interpolation Example 1 Points');

xlabel('point');

ylabel('sin(x)');

x = 0:100; %Original Data Points

y = sin(x); % sin of original data points

xi = 0:.25:100; % points to interpolate

yi = interp1(x,y,xi); % interpolated vector

subplot(3,1,2);

plot(x,y,'o',xi,yi,'.-r')

title('Interpolation Example 3 Points');

xlabel('point');

ylabel('sin(x)');

x = 0:100; %Original Data Points

y = sin(x); % sin of original data points

xi = 0:.1:100; % points to interpolate

yi = interp1(x,y,xi); % interpolated vector

subplot(3,1,3);

plot(x,y,'o',xi,yi,'.-g')

title('Interpolation Example 9 Points');

xlabel('point');

ylabel('sin(x)');