mirror of
https://github.com/ruby/ruby.git
synced 2022-11-09 12:17:21 -05:00
* lib/matrix: Add LUP decomposition
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@32353 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
parent
59a3d59496
commit
c8e2388257
4 changed files with 243 additions and 0 deletions
|
@ -1,3 +1,7 @@
|
|||
Fri Jul 1 15:23:00 2011 Marc-Andre Lafortune <ruby-core@marc-andre.ca>
|
||||
|
||||
* lib/matrix: Add LUP decomposition
|
||||
|
||||
Fri Jul 1 15:21:14 2011 Marc-Andre Lafortune <ruby-core@marc-andre.ca>
|
||||
|
||||
* lib/matrix.rb: Allow non integer exponents for Matrix#**
|
||||
|
|
3
NEWS
3
NEWS
|
@ -159,12 +159,15 @@ with all sufficient information, see the ChangeLog file.
|
|||
* matrix
|
||||
* new classes:
|
||||
* Matrix::EigenvalueDecomposition
|
||||
* Matrix::LUPDecomposition
|
||||
* new methods:
|
||||
* Matrix#diagonal?
|
||||
* Matrix#eigen
|
||||
* Matrix#eigensystem
|
||||
* Matrix#hermitian?
|
||||
* Matrix#lower_triangular?
|
||||
* Matrix#lup
|
||||
* Matrix#lup_decomposition
|
||||
* Matrix#normal?
|
||||
* Matrix#orthogonal?
|
||||
* Matrix#permutation?
|
||||
|
|
|
@ -98,6 +98,8 @@ end
|
|||
# Matrix decompositions:
|
||||
# * <tt> #eigen </tt>
|
||||
# * <tt> #eigensystem </tt>
|
||||
# * <tt> #lup </tt>
|
||||
# * <tt> #lup_decomposition </tt>
|
||||
#
|
||||
# Complex arithmetic:
|
||||
# * <tt> conj </tt>
|
||||
|
@ -122,6 +124,7 @@ class Matrix
|
|||
include Enumerable
|
||||
include ExceptionForMatrix
|
||||
autoload :EigenvalueDecomposition, "matrix/eigenvalue_decomposition"
|
||||
autoload :LUPDecomposition, "matrix/lup_decomposition"
|
||||
|
||||
# instance creations
|
||||
private_class_method :new
|
||||
|
@ -1187,6 +1190,21 @@ class Matrix
|
|||
end
|
||||
alias eigen eigensystem
|
||||
|
||||
#
|
||||
# Returns the LUP decomposition of the matrix; see +LUPDecomposition+.
|
||||
# a = Matrix[[1, 2], [3, 4]]
|
||||
# l, u, p = a.lup
|
||||
# l.lower_triangular? # => true
|
||||
# u.upper_triangular? # => true
|
||||
# p.permutation? # => true
|
||||
# l * u == a * p # => true
|
||||
# a.lup.solve([2, 5]) # => Vector[(1/1), (1/2)]
|
||||
#
|
||||
def lup
|
||||
LUPDecomposition.new(self)
|
||||
end
|
||||
alias lup_decomposition lup
|
||||
|
||||
#--
|
||||
# COMPLEX ARITHMETIC -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
|
||||
#++
|
||||
|
|
218
lib/matrix/lup_decomposition.rb
Normal file
218
lib/matrix/lup_decomposition.rb
Normal file
|
@ -0,0 +1,218 @@
|
|||
class Matrix
|
||||
# Adapted from JAMA: http://math.nist.gov/javanumerics/jama/
|
||||
|
||||
#
|
||||
# For an m-by-n matrix A with m >= n, the LU decomposition is an m-by-n
|
||||
# unit lower triangular matrix L, an n-by-n upper triangular matrix U,
|
||||
# and a m-by-m permutation matrix P so that L*U = P*A.
|
||||
# If m < n, then L is m-by-m and U is m-by-n.
|
||||
#
|
||||
# The LUP decomposition with pivoting always exists, even if the matrix is
|
||||
# singular, so the constructor will never fail. The primary use of the
|
||||
# LU decomposition is in the solution of square systems of simultaneous
|
||||
# linear equations. This will fail if singular? returns true.
|
||||
#
|
||||
|
||||
class LUPDecomposition
|
||||
# Returns the lower triangular factor +L+
|
||||
|
||||
include Matrix::ConversionHelper
|
||||
|
||||
def l
|
||||
Matrix.build(@row_size, @col_size) do |i, j|
|
||||
if (i > j)
|
||||
@lu[i][j]
|
||||
elsif (i == j)
|
||||
1
|
||||
else
|
||||
0
|
||||
end
|
||||
end
|
||||
end
|
||||
|
||||
# Returns the upper triangular factor +U+
|
||||
|
||||
def u
|
||||
Matrix.build(@col_size, @col_size) do |i, j|
|
||||
if (i <= j)
|
||||
@lu[i][j]
|
||||
else
|
||||
0
|
||||
end
|
||||
end
|
||||
end
|
||||
|
||||
# Returns the permutation matrix +P+
|
||||
|
||||
def p
|
||||
rows = Array.new(@row_size){Array.new(@col_size, 0)}
|
||||
@pivots.each_with_index{|p, i| rows[i][p] = 1}
|
||||
Matrix.send :new, rows, @col_size
|
||||
end
|
||||
|
||||
# Returns +L+, +U+, +P+ in an array
|
||||
|
||||
def to_ary
|
||||
[l, u, p]
|
||||
end
|
||||
alias_method :to_a, :to_ary
|
||||
|
||||
# Returns the pivoting indices
|
||||
|
||||
attr_reader :pivots
|
||||
|
||||
# Returns +true+ if +U+, and hence +A+, is singular.
|
||||
|
||||
def singular? ()
|
||||
@col_size.times do |j|
|
||||
if (@lu[j][j] == 0)
|
||||
return true
|
||||
end
|
||||
end
|
||||
false
|
||||
end
|
||||
|
||||
# Returns the determinant of +A+, calculated efficiently
|
||||
# from the factorization.
|
||||
|
||||
def det
|
||||
if (@row_size != @col_size)
|
||||
Matrix.Raise Matrix::ErrDimensionMismatch unless square?
|
||||
end
|
||||
d = @pivot_sign
|
||||
@col_size.times do |j|
|
||||
d *= @lu[j][j]
|
||||
end
|
||||
d
|
||||
end
|
||||
alias_method :determinant, :det
|
||||
|
||||
# Returns +m+ so that <tt>A*m = b</tt>,
|
||||
# or equivalently so that <tt>L*U*m = P*b</tt>
|
||||
# +b+ can be a Matrix or a Vector
|
||||
|
||||
def solve b
|
||||
if (singular?)
|
||||
Matrix.Raise Matrix::ErrNotRegular, "Matrix is singular."
|
||||
end
|
||||
if b.is_a? Matrix
|
||||
if (b.row_size != @row_size)
|
||||
Matrix.Raise Matrix::ErrDimensionMismatch
|
||||
end
|
||||
|
||||
# Copy right hand side with pivoting
|
||||
nx = b.column_size
|
||||
m = @pivots.map{|row| b.row(row).to_a}
|
||||
|
||||
# Solve L*Y = P*b
|
||||
@col_size.times do |k|
|
||||
(k+1).upto(@col_size-1) do |i|
|
||||
nx.times do |j|
|
||||
m[i][j] -= m[k][j]*@lu[i][k]
|
||||
end
|
||||
end
|
||||
end
|
||||
# Solve U*m = Y
|
||||
(@col_size-1).downto(0) do |k|
|
||||
nx.times do |j|
|
||||
m[k][j] = m[k][j].quo(@lu[k][k])
|
||||
end
|
||||
k.times do |i|
|
||||
nx.times do |j|
|
||||
m[i][j] -= m[k][j]*@lu[i][k]
|
||||
end
|
||||
end
|
||||
end
|
||||
Matrix.send :new, m, nx
|
||||
else # same algorithm, specialized for simpler case of a vector
|
||||
b = convert_to_array(b)
|
||||
if (b.size != @row_size)
|
||||
Matrix.Raise Matrix::ErrDimensionMismatch
|
||||
end
|
||||
|
||||
# Copy right hand side with pivoting
|
||||
m = b.values_at(*@pivots)
|
||||
|
||||
# Solve L*Y = P*b
|
||||
@col_size.times do |k|
|
||||
(k+1).upto(@col_size-1) do |i|
|
||||
m[i] -= m[k]*@lu[i][k]
|
||||
end
|
||||
end
|
||||
# Solve U*m = Y
|
||||
(@col_size-1).downto(0) do |k|
|
||||
m[k] = m[k].quo(@lu[k][k])
|
||||
k.times do |i|
|
||||
m[i] -= m[k]*@lu[i][k]
|
||||
end
|
||||
end
|
||||
Vector.elements(m, false)
|
||||
end
|
||||
end
|
||||
|
||||
def initialize a
|
||||
raise TypeError, "Expected Matrix but got #{a.class}" unless a.is_a?(Matrix)
|
||||
# Use a "left-looking", dot-product, Crout/Doolittle algorithm.
|
||||
@lu = a.to_a
|
||||
@row_size = a.row_size
|
||||
@col_size = a.column_size
|
||||
@pivots = Array.new(@row_size)
|
||||
@row_size.times do |i|
|
||||
@pivots[i] = i
|
||||
end
|
||||
@pivot_sign = 1
|
||||
lu_col_j = Array.new(@row_size)
|
||||
|
||||
# Outer loop.
|
||||
|
||||
@col_size.times do |j|
|
||||
|
||||
# Make a copy of the j-th column to localize references.
|
||||
|
||||
@row_size.times do |i|
|
||||
lu_col_j[i] = @lu[i][j]
|
||||
end
|
||||
|
||||
# Apply previous transformations.
|
||||
|
||||
@row_size.times do |i|
|
||||
lu_row_i = @lu[i]
|
||||
|
||||
# Most of the time is spent in the following dot product.
|
||||
|
||||
kmax = [i, j].min
|
||||
s = 0
|
||||
kmax.times do |k|
|
||||
s += lu_row_i[k]*lu_col_j[k]
|
||||
end
|
||||
|
||||
lu_row_i[j] = lu_col_j[i] -= s
|
||||
end
|
||||
|
||||
# Find pivot and exchange if necessary.
|
||||
|
||||
p = j
|
||||
(j+1).upto(@row_size-1) do |i|
|
||||
if (lu_col_j[i].abs > lu_col_j[p].abs)
|
||||
p = i
|
||||
end
|
||||
end
|
||||
if (p != j)
|
||||
@col_size.times do |k|
|
||||
t = @lu[p][k]; @lu[p][k] = @lu[j][k]; @lu[j][k] = t
|
||||
end
|
||||
k = @pivots[p]; @pivots[p] = @pivots[j]; @pivots[j] = k
|
||||
@pivot_sign = -@pivot_sign
|
||||
end
|
||||
|
||||
# Compute multipliers.
|
||||
|
||||
if (j < @row_size && @lu[j][j] != 0)
|
||||
(j+1).upto(@row_size-1) do |i|
|
||||
@lu[i][j] = @lu[i][j].quo(@lu[j][j])
|
||||
end
|
||||
end
|
||||
end
|
||||
end
|
||||
end
|
||||
end
|
Loading…
Reference in a new issue