fxm=smoothmultR(fx,c,m,r)

function fxm=smoothmultR(fx,c,m,r)
%Smooth Function Multiplier--Right side only
%Multiplies a section of a function, fx, by a constant, c, but keeps the function
%smooth and continuous
%fx is multiplited by c at the center of the section, and the multiplier decreases
%quadratically to 1 at the two boundary points
%
% Appropriate citation:
% Prause, N., Williams, K., & Bosworth, K. (2009). Wavelet denoising of
% vaginal pulse amplitude. Psychophysiology, in press.
%
%USAGE:
%           fxm=smoothmult(fx,c,m,r)
%INPUTS:
%           fx: the function in question,                   Array
%           c:  the constant of multiplication,             Scalar
%           m:  the center of the section to be multiplied, Scalar
%           r:  the radius of the section to be multiplied, Scalar
%OUTPUT:
%           fxm:the function multiplied across a section by the
%           multiplication constant
%
%NOTE:  if you have two boundary points, x1 and x2, m and r can be found:
%           m=(x2+x1)/2
%           r=(x2-x1)/2

%find boundaries
x1=m;
x2=m+r;

fxm=fx;
u=1:length(fx);     %dependent dummy variable
Mx=ones(1,length(fx));
Mx(x1:x2)=((1-c)/r.^2).*(u(x1:x2)-m).^2+c;

%works for both vertical and horizontal arrays
[xs,ys]=size(fx);
if ys==1
    Mx=Mx';
end

fxm(x1:x2)=fx(x1:x2).*Mx(x1:x2);