Opened 5 years ago

Last modified 4 years ago

## #21655 new enhancement

# Return (d/dn)f with f(n,x).diff(n) instead of runtime error

Reported by: | rws | Owned by: | |
---|---|---|---|

Priority: | major | Milestone: | sage-7.4 |

Component: | symbolics | Keywords: | |

Cc: | Merged in: | ||

Authors: | Reviewers: | ||

Report Upstream: | N/A | Work issues: | |

Branch: | Commit: | ||

Dependencies: | Stopgaps: |

### Description

Expected behaviour:

sage: hermite(n,x).diff(n) diff(hermite(n, x), n)

for all cases where we throw runtime or not implemented errors at the moment. This concerns mostly orthogonal poly functions. The aim is a better workflow for the user, with no interrupts.

### Change History (3)

### comment:1 Changed 5 years ago by

### comment:2 Changed 5 years ago by

The runtime errors are partly thrown in Pynac, they should return `fderivative`

instead like is done with anonymous functions:

sage: f=function('f')(x) sage: diff(f,x) diff(f(x), x) sage: _._dbgprinttree() fderivative f @0x3dc6b00, hash=0x1023d72de5409a, flags=0xb, nops=1, params=0 x (symbol) @0x3049d20, serial=5, hash=0xf0a9622e, flags=0xf, domain=0, iflags=0000000000000000 =====

The others are errors thrown in Python. I'm not sure which will be simple to change.

### comment:3 Changed 4 years ago by

May depend on #24861.

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Do you have an idea about what needs to be done in case someone decides to work on this? Ie, some tips about how to start?