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QuickStart Samples

Matrix-Vector Operations QuickStart Sample (IronPython)

Illustrates how to perform operations that involve both matrices and vectors in IronPython.

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import numerics

from Extreme.Mathematics import *

# The Vector and DenseMatrix classes reside in the 
# Extreme.Mathematics.LinearAlgebra namespace.
from Extreme.Mathematics.LinearAlgebra import *

#/ Illustrates operations on DenseMatrix objects and combined
#/ operations on Vector and DenseMatrix objects from the
#/ Extreme.Mathematics.LinearAlgebra namespace of the Extreme Optimization
#/ Mathematics Library for .NET.

# For details on the basic workings of Vector 
# objects, including constructing, copying and
# cloning vectors, see the BasicVectors QuickStart
# Sample.
#
# For details on the basic workings of DenseMatrix
# objects, including constructing, copying and
# cloning vectors, see the BasicVectors QuickStart
# Sample.
#
# Let's create some vectors to work with.
v1 = Vector([1, 2, 3, 4, 5])
v2 = Vector([1, -2, 3, -4, 5])
print "v1 = {0:.4f}".format(v1)
print "v2 = {0:.4f}".format(v2)

# Also, here are a couple of matrices.
# We start out with a 5x5 identity matrix:
m1 = DenseMatrix.GetIdentity(5)
# Now we use the GetDiagonal method and combine it
# with the SetValue method of the Vector class to
# set some of the off-diagonal elements:
m1.GetDiagonal(1).SetValue(2)
m1.GetDiagonal(2).SetValue(3)
m1.GetDiagonal(-1).SetValue(4)
print "m1 = {0:.4f}".format(m1)
# We define our second matrix by hand:
m2 = Matrix([[1,1,1,1,1], [2,3,4,8,-1], [3,5,9,27,1], [4,7,16,64,-1], [5,9,25,125,1]])
print "m2 = {0:.4f}".format(m2)
print 
			
#
# Matrix arithmetic
#

# The Matrix class defines operator overloads for
# addition, subtraction, and multiplication of
# matrices.

# Addition:
print "Matrix arithmetic:"
m = m1 + m2
print "m1 + m2 = {0:.4f}".format(m)
# Subtraction:
m = m1 - m2
print "m1 - m2 = {0:.4f}".format(m)
# Multiplication is the True matrix product:
m = m1 * m2
print "m1 * m2 = {0:.4f}".format(m)
print 

#
# Matrix-Vector products
#

# The DenseMatrix class defines overloaded addition, # subtraction, and multiplication operators 
# for vectors and matrices:
print "Matrix-vector products:"
v = m1 * v1
print "m1 v1 = {0:.4f}".format(v)
# You can also multiply a vector by a matrix on the right.
# This is equivalent to multiplying on the left by the 
# transpose of the matrix:
v = v1 * m1
print "v1 m1 = {0:.4f}".format(v)
			
# Now for some methods of the Vector class that
# involve matrices:
# Add a product of a matrix and a vector:
v.Add(m1, v1)
print "v + m1 v1 = {0:.4f}".format(v)
# Or add a scaled product:
v.Add(-2, m1, v2)
print "v - 2 m1 v2 = {0:.4f}".format(v)
# You can also use static Subtract methods:
v.Subtract(m1, v1)
print "v - m1 v1 = {0:.4f}".format(v)
print 

#
# Matrix norms
#
print "Matrix norms"
# Matrix norms are not as easily defined as
# vector norms. Three matrix norms are available.
# 1. The one-norm through the OneNorm property:
a = m2.OneNorm()
print "OneNorm of m2 = {0:.4f}".format(a)
# 2. The infinity norm through the 
#    InfinityNorm property:
a = m2.InfinityNorm()
print "InfinityNorm of m2 = {0:.4f}".format(a)
# 3. The Frobenius norm is often used because it
#    is easy to calculate.
a = m2.FrobeniusNorm()
print "FrobeniusNorm of m2 = {0:.4f}".format(a)
print 

# The trace of a matrix is the sum of its diagonal
# elements. It is returned by the Trace property:
a = m2.Trace()
print "Trace(m2) = {0:.4f}".format(a)

# The Transpose method returns the transpose of a 
# matrix. This transposed matrix shares element storage
# with the original matrix. Use the CloneData method
# to give the transpose its own data storage.
m = m2.Transpose()
print "Transpose(m2) = {0:.4f}".format(m)