Quick 1-D linear interpolation
Note: interp1q is not recommended. Use interp1 instead.
yi = interp1q(x,Y,xi)
yi = interp1q(x,Y,xi) returns the value of the 1-D function Y at the points of column vector xi using linear interpolation. The vector x specifies the coordinates of the underlying interval. The length of output yi is equal to the length of xi.
interp1q is quicker than interp1 on non-uniformly spaced data because it does no input checking.
For interp1q to work properly,
x must be a monotonically increasing column vector.
Y must be a column vector or matrix with length(x) rows.
xi must be a column vector
interp1q returns NaN for any values of xi that lie outside the coordinates in x. If Y is a matrix, then the interpolation is performed for each column of Y, in which case yi is length(xi)-by-size(Y,2).
Generate a coarse sine curve and interpolate over a finer abscissa.
x = (0:10)'; y = sin(x); xi = (0:.25:10)'; yi = interp1q(x,y,xi); plot(x,y,'o',xi,yi)