Update to qfsolve doc

["Thomas D. Dean" <tomdean@wavecable.com>]

Here is s suggested patch to doc to reflect the 'extera' argument to 
qfsolve.


Tom Dean

*** usersch3.tex~	2023-12-09 17:05:02.737511515 -0800
--- usersch3.tex	2023-12-14 13:35:16.753248824 -0800
***************
*** 14688,14693 ****
--- 14688,14698 ----
  where $F$ is the factorization matrix of the absolute value of the determinant
  of $G$.
  
+ $G$ may be a vector [$G$,$F$] where $G$ is a symmetric matrix similar
+ to matdigonal([1,1,...,1,-$n$]) and $F$ is matrix of the factors of
+ $n$. Then, $F$ will be used to reduce the number of factorizations in
+ solving the quadratic equation.
+ 
  The solution might be a single nonzero column vector
  (\typ{COL}) or a matrix (whose columns generate a totally isotropic
  subspace).
***************
*** 37052,37055 ****
  This function is obsolete, use plothrawexport and write the result to file.
  
  The library syntax is \fun{GEN}{psplothraw}{GEN listx, GEN listy, long flag}.
! \vfill\eject
\ No newline at end of file
--- 37057,37060 ----
  This function is obsolete, use plothrawexport and write the result to file.
  
  The library syntax is \fun{GEN}{psplothraw}{GEN listx, GEN listy, long flag}.
! \vfill\eject