2019-08-25 23:04:25 +0200 | received badge | ● Student (source) |

2019-08-25 22:48:45 +0200 | asked a question | Inverse of real sparse matrix Dear sagemath community, I'm a bit surprised in the result that I obtain when I compute the inverse of a real, sparse matrix. The problem occurs in Sagemath 8.7, (on windows). In my case the matrix is The result is 138.4999999999923, which is very far from the expected value: 1. If one replaces sparse=true by sparse=false, the result becomes reasonable.The problem also does not occur when I replace RR by QQ. I suspect that this will not happen in all versions of Sagemath, since I stumbled upon this strange behaviour when I was executing a code that used to work fine years ago. Sadly I do not recall which version I used to have back then. I wanted to ask: what is currently the right way to compute the inverse of a sparse real matrix? cheers, IV |

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