gram.m

similer program for matlab

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##               Auburn University. All rights reserved.
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## -*- texinfo -*-
## @deftypefn {Function File} {} gram (@var{a}, @var{b})
## Return controllability gramian @var{m} of the continuous time system
## @math{dx/dt = a x + b u}.
##
## @var{m} satisfies @math{a m + m a' + b b' = 0}.
## @end deftypefn

## Author: A. S. Hodel <[e-mail]>

function m = gram (a, b)

  if (nargin != 2)
    print_usage ();
  endif

  ## Let lyap do the error checking...

  m = lyap (a, b*b');

endfunction