Rational power of a positive definite matrix

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Qian Feng 2017-2-13

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评论： Qian Feng 2017-2-13

采纳的回答： John D'Errico

q = sym([4 2 ; 2 4]);

f = sqrtm(q)^(-1) - sqrtm(q^(-1));

f should be zero here since q is positive definite.

However, the program yielded a non zero f here. Is this due to the calculation error ? Note that I am using symbolic calculation here so there should be no error at all I assume.

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John D'Errico 2017-2-13

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编辑：John D'Errico 2017-2-13

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Sometimes the answer is just "simple".

simplify(f)
ans =
[ 0, 0]
[ 0, 0]

Symbolic results are not always returned in the most simple possible form.

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Qian Feng 2017-2-13

Thanks for the suggestion. I should have realized that.

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