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commented
9 years ago Here is code that adds this functionality:
def determinant(self):
return (a*f*k
+ b*g*i
+ c*e*j
- a*g*j
- b*e*k
- c*f*i)
def inverse(self):
tmp = Matrix3()
d = self.determinant()
if abs(d) < 0.001:
# No inverse, return identity
return tmp
else:
d = 1.0 / d
tmp.a = d * (self.f*self.k - self.g*self.j)
tmp.b = d * (self.c*self.j - self.b*self.k)
tmp.c = d * (self.b*self.g - self.c*self.f)
tmp.e = d * (self.g*self.i - self.e*self.k)
tmp.f = d * (self.a*self.k - self.c*self.i)
tmp.g = d * (self.c*self.e - self.a*self.g)
tmp.i = d * (self.e*self.j - self.f*self.i)
tmp.j = d * (self.b*self.i - self.a*self.j)
tmp.k = d * (self.a*self.f - self.b*self.e)
return tmp
This code was automatically created by the following program:
#!/usr/bin/python
"""
Create code for determinant and inversion of a 3x3 matrix
for pyeuclid.
This code is in the public domain.
Dov Grobgeld <dov.grobgeld@gmail.com>
Saturday 2011-03-12 23:44
"""
import sympy
import re
syms = 'abcefgijk'
for v in syms:
locals()[v]=sympy.Symbol(v)
M = sympy.Matrix([[a,b,c],
[e,f,g],
[i,j,k]])
# Create determinant and rewrite the string expression
det = M.det()
expr = re.sub(r'([\+\-])', '\n \\1',
re.sub(r"\b(["+syms+"])\b", r'self.\1',
str(det)))
print " def determinant(self):"
print " return (" + expr + ")"
print """
def inverse(self):
tmp = Matrix3()
d = self.determinant()
if abs(d) < 0.001:
# No inverse, return identity
return tmp
else:
d = 1.0 / d
"""
# Invert, rewrite, and output
Minv = sympy.cancel(det*M.inv())
for idx in range(9):
expr = Minv[idx]
print (" tmp."
+syms[idx]
+" = d * ("
+re.sub(r"\b([abcefgijk])\b", r'self.\1', str(expr))
+")")
print "\n return tmp"
Original comment by dov.grob...@gmail.com on 12 Mar 2011 at 9:44
Original issue reported on code.google.com by
dov.grob...@gmail.comon 26 Feb 2011 at 10:53