src/numerics/sweep.lisp

   1 ;;; -*- mode: lisp -*-
   2
   3 ;;; Time-stamp: <2009-01-17 18:00:55 tony>
   4 ;;; Creation:   <2008-03-11 19:18:34 user>
   5 ;;; File:       packages.lisp
   6 ;;; Author:     AJ Rossini <blindglobe@gmail.com>
   7 ;;; Copyright:  (c)2009--, AJ Rossini.  BSD, LLGPL, or GPLv2, depending
   8 ;;;             on how it arrives.
   9 ;;; Purpose:    sweep operator implementation.
  10
  11 ;;; What is this talk of 'release'? Klingons do not make software
  12 ;;; 'releases'.  Our software 'escapes', leaving a bloody trail of
  13 ;;; designers and quality assurance people in its wake.
  14
  15 ;;; This organization and structure is new to the 21st Century
  16 ;;; version.
  17
  18
  19 (in-package :lisp-stat-numerics-sweep)
  20
  21 ;; macros
  22
  23 ;; internal:  divide up the operator strategy to handle the variety of
  24 ;; possibilities that we consider for analysis of the matrix, in
  25 ;; prticular we needf to think about what it is that we want to do to
  26 ;; identify the matrix
  27
  28 (defun op-swap-rows (m r1n r2n))
  29
  30 (defun op-scalar-mult-row (m s r))
  31
  32 (defun op-subtract-rows (m r1 r2))
  33
  34
  35
  36 ;; external
  37 (defun sweep-operator (m type)
  38   "Return the swept matrix n.
  39
  40    The basic idea behind the sweep operator is that we can get a
  41  matrix A converted to I in a few steps.  It is critical that we can
  42  figure out the general approach for the algorithm, as doing it in
  43  line, i.e. [A|I] => [I|A^*] means we can probably do something a bit
  44  more like [A] => [A^*], since the original operations work on a
  45  column-by-column basis."
  46   (let ((n (copy! m)))
  47     (dotimes (i (nrows m))
  48       (set-ith-ith-entry-to-1 n)
  49       (zero-other-entries))
  50     n))