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#172 bezout.spad.pamphlet and Knuth's reference ←	↑	→ #174 (1 . failed) cannot be coerced to mode (Integer) in TriangularMatrixOperations

#173 (1 . failed) cannot be coerced to mode (Integer) in TriangularMatrixOperations

Edit detail for #173 (1 . failed) cannot be coerced to mode (Integer) in TriangularMatrixOperations revision 2 of 2

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Editor: test1 Time: 2014/04/23 19:10:36 GMT+0
Note:

added:

From test1 Wed Apr 23 19:10:36 +0000 2014
From: test1
Date: Wed, 23 Apr 2014 19:10:36 +0000
Subject: 
Message-ID: <20140423191036+0000@axiom-wiki.newsynthesis.org>

Severity: normal => wishlist

From functions's declaration:

    UpTriBddDenomInv: (M,R) -> M
      ++ UpTriBddDenomInv(B,d) returns M, where
      ++ B is a non-singular upper triangular matrix and d is an
      ++ element of R such that \spad{M = d * inv(B)} has entries in R.

Here, it's false, but may be use another error message

fricas

(1) -> a:=matrix ([[1,2],[0,9]])

$\label{eq1}\left[ \begin{array}{cc} 1 & 2 \ 0 & 9$

(1)

Type: Matrix(NonNegativeInteger?)

fricas

inverse(a)

$\label{eq2}\left[ \begin{array}{cc} 1 & -{\frac{2}{9}} \ 0 &{\frac{1}{9}}$

(2)

Type: Union(Matrix(Fraction(Integer)),...)

fricas

)expose TriangularMatrixOperations

   TriangularMatrixOperations is now explicitly exposed in frame 
      initial 
UpTriBddDenomInv(a,9)

$\label{eq3}\left[ \begin{array}{cc} 9 & - 2 \ 0 & 1$

(3)

Type: Matrix(Integer)

fricas

UpTriBddDenomInv(a,7)

   >> Error detected within library code:
   "failed" of mode Union(Integer,"failed") cannot be coerced to mode Integer

fricas

a:=matrix ([[1,2],[0,9]])

$\label{eq4}\left[ \begin{array}{cc} 1 & 2 \ 0 & 9$

(4)

Type: Matrix(NonNegativeInteger?)

fricas

a:=transpose(a)

$\label{eq5}\left[ \begin{array}{cc} 1 & 0 \ 2 & 9$

(5)

Type: Matrix(NonNegativeInteger?)

fricas

inverse(a)

$\label{eq6}\left[ \begin{array}{cc} 1 & 0 \ -{\frac{2}{9}}&{\frac{1}{9}}$

(6)

Type: Union(Matrix(Fraction(Integer)),...)

fricas

LowTriBddDenomInv(a,9)

$\label{eq7}\left[ \begin{array}{cc} 9 & 0 \ - 2 & 1$

(7)

Type: Matrix(Integer)

fricas

LowTriBddDenomInv(a,7)

   >> Error detected within library code:
   "failed" of mode Union(Integer,"failed") cannot be coerced to mode Integer

what's wrong with that? --unknown, Fri, 01 Jul 2005 03:05:23 -0500 reply

From the package:

  ++ This package provides functions that compute "fraction-free"
  ++ inverses of upper and lower triangular matrices over a integral
  ++ domain. By "fraction-free inverse" we mean the following:
  ++ given a matrix B with entries in R and an element d of R such that
  ++ d* inv(B) also has entries in R, we return d * inv(B).

So if you enter B and d such that d * inv(B) does not have entries in R, it is an error. The package is for internal use (that why it is not exposed) where d is always divisible by the determinant of B.

I know it is false but... --unknown, Sun, 10 Jul 2005 10:02:41 -0500 reply

But I don't like computer error. I prefer some mathematical message for example:

d is not an element of R such that \spad{M = d * inv(B)} has entries in R.

... --test1, Wed, 23 Apr 2014 19:10:36 +0000 reply

Severity: normal => wishlist