fitlag polcof polint polyvl

polint() void polint ( int  n, double  x[], double  y[], double  c[], int *  info  ) Produces a polynomial interpolation Purpose This routine produces a polynomial which interpolates a set of discrete data points. polint sets up information in the array c[] which can be used by subroutine polyvl to evaluate the polynomial and its derivatives and by subroutine polcof to produce the coefficients. Parameters [in] n Number of data points. (n >= 1) [in] x[] Array x[lx] (lx >= n) The array of abscissas. (All of which must be distinct) [in] y[] Array y[ly] (ly >= n) The array of ordinates. [out] c[] Array c[lc] (lc >= n) An array of information used by subroutines polyvl and polcof. [out] info = 0: Successful exit = -1: The argument n had an illegal value (n < 1) = 1: The abscissas are not distinct Reference SLATEC