MacFormat 1994 August/August CD.bin/Shareware/Education/numericalmethods Folder/chap_5/cs.m

Text File | 1994-06-05 | 533 b | 29 lines | [MATF/MATL]

function Z = cs(S,X,T)
% Z = cs(S,X,T)
% Evaluates the spline created with csfit.m
% S coefficient list, input.
% X is the vector of abscissas, input.
% T is the input value(s), input.
% Z is the function value(s), output.
n = length(X)-1;
m = length(T);
Z = zeros(1,m);
for i=1:m,
  t = T(i);
  j = 0;
  k = n-1;
  while (j<=n-1);
    j=j+1;
    if (t<=X(j+1)),
      k=j-1;
      j=n+1;
    end
  end
  if (t<=X(1)),
    k = 0;
  end
  w = t-X(k+1);
  z=((S(k+1,3+1)*w + S(k+1,2+1))*w + S(k+1,1+1))*w + S(k+1,0+1);
  Z(i) = z;
end