Opened 5 years ago

## #21873 new defect

# (Maxima's) solve is unable to solve a linear system with complicated coefficients

Reported by: | charpent | Owned by: | |
---|---|---|---|

Priority: | major | Milestone: | sage-7.5 |

Component: | symbolics | Keywords: | maxima solve |

Cc: | Merged in: | ||

Authors: | Reviewers: | ||

Report Upstream: | Reported upstream. No feedback yet. | Work issues: | |

Branch: | Commit: | ||

Dependencies: | Stopgaps: |

### Description

Long story : see this sage-support thread.

Short story : Let M_x be the matrix representing a rotation of angle theta about the x axis (in `R^3`

```
), and M_y the matrix representing a rotation of angle phi about the y axis. Trying to find by elementary methods the axis of the composition, i. e. solving M_y*M_x*V-V for V, the only solution found its the trivial null vector.
```

This has been reproduced in Maxima and reported on their bug system as bugs:3239, with no answer at the time of the present filing.

This can be worked around by using Sympy's solve, which involves some conversions using _sage_() (not *that* well documented).

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