% evaluate a polynomial and its error bound
% function [val,errorbound] = polyvalbnd(coef,x)
% Inputs:
% coef = array of polynomial coefficients, starting with highest order
% x = (array of) argument
% Outputs:
% val = value of polynomial = polyval(coef,x)
% errorbound = bound on roundoff error in polynomial evaluation
% = 2*degree*macheps*polyval(abs(coeff),abs(x))
function [val,errorbound] = polyvalbnd(coef,x)
val = polyval(coef,x);
errorbound = .5*eps*polyval(abs(coef),abs(x));