backsolve2

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backsolve2

$\begin{usage} backsolve2(a,p,st,r,c,d)\\ backsolve2(a,p,st,r,b,d) \end{usage}$

$\begin{signatures} backsolve2:& (M,Z $\to$\ Z,\htmlref{\texttt{PrimitiveArray}... ...rray} Z,Z,M,R)$\to$(M,\htmlref{\texttt{Vector}}{Vector} R)\\\end{signatures}$

$\begin{params} {\em a} & M & A matrix representing a Row Echelon Form (REF)\\ ... ...} & R & A maximal denominator needed for a dependence relation\\\end{params}$

where
Z == MachineInteger

$\begin{descr} Backsolves a triangular system in a minimal way. The triple $(a,... ...rm th}}$\ column is called leading if $j=st(i)$\ for some $i$).\\\end{descr}$

$\begin{retval} backsolve2(a,p,st,r,c,d) returns a primitive vector $v$\ such t... ... $s(j,l)\neq 0$\ only if the ${j}^{{\rm th}}$\ column is leading.\end{retval}$

Manuel Bronstein 2000-12-13