polynInterp(xy, x)

Neville's algorithm to interpolate without calculating the coefficients.

xyIt is a matrix the first column of which contains the x values, the second contains the corresponding y values. It is expected to be sorted by x.
return valueInterpolating polynomial.

In comparison, the function polynLagrange calculates the coefficients, and hence is probably more efficient for many evaluation of the same interpolating polynomial.

xy = [-1,4; 4,8; 42,-88; 444, 827]; xunit = 1J; yunit = 1V; xmin = min(xy[...;0]); xmax = max(xy[...;0]); eps = (xmax-xmin)/200; xmin -= 2*eps; xmax += 2*eps; x = (xmin..eps..xmax)*xunit; y = (@(x) polynInterp(xy * [xunit,0;0,yunit], x))(#x); plot(x,y)