To interpoolate a matrix of row vectors, something like this will work:
Vectors = rand(4, 10); % Concatenated Into Matrix Of 4 Rows, 10 Columns
Toriginal = 1:10; % Original Independent Variable Vector
newT = linspace(min(Toriginal), max(Toriginal), 25); % Independent Variable To Interpolate
newVectors = interp1(Toriginal', Vectors', newT, 'linear', 'extrap')'; % Interpolated Vectors
The original row vectors must be transposed to column vectors for the interp1 (link) function. This transposes them, does the interpolation, and then transposes them back to row vectors. If they are already column vectors, the transpositions are not necessary.
