rhobiweight(x,c)

function rho = rhobiweight(x,c)

% Computes Tukey's biweight rho function with constant c for all
% values in the vector x.

hulp = x.^2/2-x.^4/(2*c^2)+x.^6/(6*c^4);
rho = hulp.*(abs(x)<c)+c^2/6.*(abs(x)>=c);