function A=rbf1(A,style,param)
% function A=rbf1(A,style,param)
%    param is optional for certain nonlinearities (See below)
%
%  This function applies the nonlinearity in "style" to the matrix A:
%  style=1:  Gaussian.  Param needed for width:  Default is 1
%        2:  Cubic
%        3:  Thin Plate Spline
%        4:  Cauchy
%        5:  Multiquadric.  Param needed for centering.  Default is 1
%        6:  Inverse Multiquadric.  Param needed, default is 1.

switch style
    case 1
        if nargin<=2
            sigma=1;
        else
            sigma=param;
        end
        A=exp(-(A.^2)./(param.^2));
    case 2
        A=A.^3;
    case 3
        Gidx=find(A(:)==0);
        if length(Gidx)>0
            error('The EDM in RBF1 cannot have zeros in the Thin Plate Spline');
        else
        A=(A.^2).*log(A);
        end
    case 4
        A=1./(1+A);
    case 5
        if nargin<=2
            beta=1;
        else
            beta=param;
        end
        A=sqrt(A.^2+beta);
    case 6
        if nargin<=2
            beta=1;
        else
            beta=param;
        end
        A=1./(sqrt(A.^2+beta));
        
end