mcud.m

GPS TOOLBOX包含以下内容： 1、GPS相关常量和转换因子； 2、角度变换； 3、坐标系转换： &#61656 点变换； &#61656 矩阵变换； &#61656 向量变换

%                                mcud.m
%  Scope:   This MATLAB macro computes the real symmetric matrix 
%           P = U*D*U**(Transpose), when its U-D factors are given, where U
%           is a real unit upper triangular matrix and D is a real diagonal
%           matrix. Only the upper triangular part (columnwise) of the pair
%           U-D and matrix P are stored.
%  Usage:   p = mcud(n,ud)
%           ud = mcud(n,ud) , when the input matrix  ud  is destroyed
%  Description of parameters:
%           n   - input, real scalar, number of rows and columns in matrices
%                 U , D and P
%           ud  - input, real array of length  n*(n+1)/2, storing the
%                 upper triangular part of the pair  U-D ; the elements of
%                 the diagonal matrix  D  are stored on diagonal locations
%                 of the unit upper triangular matrix  U
%           p   - output, real array of length  n*(n+1)/2, storing the
%                 upper triangular part of the resultant matrix  P
%  Remark:  The computation can be used to determine the covariance matrix 
%           from its U-D factors.
%  Last update:  06/29/00
%  Copyright (C) 1996-00 by LL Consulting. All Rights Reserved.

function  p = mcud(n,ud)

nn1 = n*(n+1)/2;
p = zeros(nn1,1);
p(1) = ud(1);
if n == 1
   return
end
jj = 1;
for j = 2:n
   jjp = jj;
   jj = jj + j;
   p(jj) = ud(jj);
   s = p(jj);
   ii = 0;
   jm1 = j - 1;
   for i = 1:jm1
      ii = ii + i;
      temp = s * ud(jjp + i);
      ik = ii;
      for k = i:jm1
         p(ik) = p(ik) + temp * ud(jjp + k);
         ik = ik + k;
      end
      p(jjp + i) = temp;
   end          
end