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Invertible matrix with integer coefficients

asked 2 years ago

DreDd gravatar image

I try to build an invertable matrix, but using the .inverse() method returns matrix with rational coefs, so is there an opportunity in sage to return the inverse matrix with integer coefficients by taking out a common factor?

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answered 2 years ago

Emmanuel Charpentier gravatar image

Do you mean something like what follows ?

sage: foo=MatrixSpace(ZZ,2).random_element()
sage: while foo.det()==0: foo=MatrixSpace(ZZ,2).random_element()
sage: foo
[-9 -1]
[ 2 -1]
sage: bar=foo.inverse() ; bar
[-1/11  1/11]
[-2/11 -9/11]
sage: gee=gcd(bar.list()) ; gee
1/11
sage: bar/gee
[-1  1]
[-2 -9]

HTH,

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answered 2 years ago

FrédéricC gravatar image

Maybe like that

M=matrix(ZZ,2,2,[1,-1,1,0])
M.inverse_of_unit()
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Asked: 2 years ago

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Last updated: Dec 04 '22