my1.m

This is MATLAB program

function y=My1(x,params)
% My - short term design stress - strain curve for normal weight concrete.
% My(X,PARAMS) return a matrix which is the My at X.
% BUI DUC CHINH,10 - 5 -2000.
% Ver 1.03.
if nargin ~=2,
   error('Four arguments are required by My.');
elseif length(params)<4 
   error('My needs at least 4 parameters.');
end
a=params(1);
b=params(2);
c=params(3);
d=params(4);
y=zeros(size(x));
index1=find(x<=a);
if ~isempty(index1),
   y(index1)=(2*d*x(index1)/a)./(1+(x(index1)/a).^2);
end
index2=find((a<x) & (x<=0.0035));
if ~isempty(index2),
   y(index2)=(2*d*x(index2)/a)./(1+(x(index2)/a).^2);
end