Re: Non-commutative algebra (Re: [eigen] On a flexible API for submatrices, slicing, indexing, masking, etc.) |

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*To*: eigen@xxxxxxxxxxxxxxxxxxx*Subject*: Re: Non-commutative algebra (Re: [eigen] On a flexible API for submatrices, slicing, indexing, masking, etc.)*From*: Christoph Hertzberg <chtz@xxxxxxxxxxxxxxxxxxxxxxxx>*Date*: Fri, 23 Dec 2016 11:15:45 +0100

On 23.12.2016 at 10:35, Peter wrote:

That brings up a question, which may only concern my work. Does Eigen actually assume, that the floating point types are commuting?

We do at several points. E.g. s1 * A * s2 * B * s3 is optimized to something equivalent to (s1*s2*s3)*(A*B)

I'm asking since I have a programme that normalizes the input of an object we physicist call Hamiltonian and it consists of anti-commuting variables, i.e. a * b == -b * a . For examples it calculates commutators consisting of matrices containing these objects and simplifies the resulting expression.

You may be interested in this feature-request: http://eigen.tuxfamily.org/bz/show_bug.cgi?id=560 Christoph -- Dipl. Inf., Dipl. Math. Christoph Hertzberg Universität Bremen FB 3 - Mathematik und Informatik AG Robotik Robert-Hooke-Straße 1 28359 Bremen, Germany Zentrale: +49 421 178 45-6611 Besuchsadresse der Nebengeschäftsstelle: Robert-Hooke-Straße 5 28359 Bremen, Germany Tel.: +49 421 178 45-4021 Empfang: +49 421 178 45-6600 Fax: +49 421 178 45-4150 E-Mail: chtz@xxxxxxxxxxxxxxxxxxxxxxxx Weitere Informationen: http://www.informatik.uni-bremen.de/robotik

**Follow-Ups**:**[eigen] Re: Non-commutative algebra***From:*Peter

**References**:**[eigen] On a flexible API for submatrices, slicing, indexing, masking, etc.***From:*Gael Guennebaud

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**Re: [eigen] On a flexible API for submatrices, slicing, indexing, masking, etc.***From:*Peter

**Re: [eigen] On a flexible API for submatrices, slicing, indexing, masking, etc.***From:*Gael Guennebaud

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