v=[0.18 3.15 0.18 0.16 0.17 0.58 0.33 ]; % example data
% the engine
nI=3; % number points to insert
N=numel(v); % initial vector size
NN=(N-1)*nI+N; % new N for augmented v
xv=linspace(1,N,NN); % uniform spacing along 1:N NN points
vv=interp1(1:N,v,xv); % linear interpolation
vvv=interp1(1:N,v,xv,'pchip'); % or pchip interpolation
Illustrate results...
plot(v,'o-')
hold on
plot(xv,vv,'x')
plot(xv,vvv,'d-')
legend('Original','Linear','PChip')
produces
"Choose your poison" as far as what interpolant you actually want.
If you have Signal Processing TB, there's also resample you could play with.
