nhat.m

This is MATLAB program

function y=Nhat(x,params)
% Nhat - short term design stress - strain curve for normal weight concrete.
% Nhat(X,PARAMS) return a matrix which is the Nhat at X.
% BUI DUC CHINH,10 - 5 -2000.
% Ver 1.03.
if nargin ~=2,
   error('Four arguments are required by Nhat.');
elseif length(params)<4 
   error('Nhat needs at least 4 parameters.');
end
a=params(1);
b=params(2);
c=params(3);
d=params(4);
y=ones(size(x))*d;
index1=find(x<=a);
if ~isempty(index1),
   y(index1)=2*0.85*(b/c)*500*x(index1)-0.85*(b/c)*500*500*x(index1).^2;
end