Ticket #6905 (closed defect: fixed)
[with patch, positive review] real(0.0r) is broken
| Reported by: | nthiery | Owned by: | mhansen |
|---|---|---|---|
| Priority: | major | Milestone: | sage-4.1.2 |
| Component: | symbolics | Keywords: | real, symbolic, plot |
| Cc: | Work issues: | ||
| Report Upstream: | Reviewers: | Nicolas M. Thiéry | |
| Authors: | Mike Hansen | Merged in: | Sage 4.1.2.alpha2 |
| Dependencies: | Stopgaps: |
Description
Implement:
sage: real(0.0r)
Note: imag(0.0r) seems to readily work (using Maxima if I read it well)!
Found after getting the following bug report from Francois Maltey:
sage: parametric_plot ((real(exp(i*a)),imag(exp(i*a))),(a,-5,5))
Raises the following warning:
verbose 0 (2999: plot.py, generate_plot_points) WARNING: When plotting, failed to evaluate function at 200 points. verbose 0 (2999: plot.py, generate_plot_points) Last error message: float' object is not callable'
and yield an empty plot. Investing this further, I got that
sage: var('a'); f = fast_float(real(exp(i*a)),a)
Yields a non callable object. Finally Mike H traced it back on IRC to real(0.0r) being broken, because 0.0r.real is an attribute, not a method.
Attachments
-
trac_6905.patch
(786 bytes) -
added by mhansen 4 years ago.
Change History
comment:1 Changed 4 years ago by mhansen
- Owner set to mhansen
- Status changed from new to assigned
- Summary changed from real(0.0r) is broken to [with patch, needs review] real(0.0r) is broken
- Authors set to Mike Hansen
comment:2 Changed 4 years ago by nthiery
- Reviewers set to Nicolas M. Thiéry
- Summary changed from [with patch, needs review] real(0.0r) is broken to [with patch, positive review] real(0.0r) is broken
This trivial patch applies smoothly, passes all test in sage/functions (and most likely elsewhere).
I am no expert of this part of sage, and from the outside it sounds a bit like a workaround. In the long run, it would sound better to fix float to have a "real" method, and have a consistent implementation of real and imag. But it is simple enough to be safe,and it solves the original problem which hurts casual users. So I put a positive review. If anyone cares, please create a new ticket.
