BIPVAL

POLYFIT can fit a polynomial of given ORDer to vectorial data, using as independent variable data index, rescaled between -1 and 1. Similarly, BIPFIT fits a bipolynomial of given orders (a matrix) to matrix data.

POLYVAL can calculate the VALues of a POLYnomial on an equidistant abscissa x, scaled between -1 and 1. Then only length(x) counts.

Similarly, BIPVAL calculates the VALues of BIPolynomial as a matrix of user defined size. For smoothing perpouses, same size can be used as original data matrix, parent to the BIPolynomial:

BIP=randn(3,4);
BIP = 3*4 matrix (bipolynomial up to Y^2, X^3)
DAT=bipval(BIP,[100,150]);

Check:
bip=bipfit(DAT,2:3);

BIP-bip

Based on: POLYVAC

See also:
BIPFIT, SURFIT