Opened 9 years ago
Last modified 7 years ago
#12302 new defect
Partial evaluation bug for callable vector functions
Reported by: | gbe | Owned by: | gbe |
---|---|---|---|
Priority: | major | Milestone: | sage-6.4 |
Component: | symbolics | Keywords: | sd35.5 |
Cc: | jason | Merged in: | |
Authors: | Reviewers: | ||
Report Upstream: | N/A | Work issues: | |
Branch: | Commit: | ||
Dependencies: | Stopgaps: |
Description (last modified by )
For callable (scalar) functions, taking sections (partial evaluation) of functions works perfectly fine; that is to say the following code works perfectly as expected:
sage: f(x,y,z) = x*y*z; f (x, y, z) |--> x*y*z sage: g(x, z) = f(y=1); g (x, z) |--> x*z
Move up to callable vector functions and taking sections breaks however:
sage: v(x, y) = [x+y, x-y]; v (x, y) |--> (x + y, x - y) sage: v(x,0) (x, x) sage: w(x) = v(y=0) TypeError
This is because all evaluation, even if partial, of a callable vector function returns a Vector_symbolic_dense. The relevant function _ _call_ _() is defined in free_module_element.pyx.
The fix, of course, is to make the code intelligent enough to know that an evaluation is only partial -- one hopes that type(vx)
would return 'sage.modules.vector_callable_symbolic_dense.Vector_callable_symbolic_dense'> rather than 'sage.modules.vector_symbolic_dense.Vector_symbolic_dense'>
sage: v(x, y) = [x+y, x-y] sage: type(v) <class 'sage.modules.vector_callable_symbolic_dense.Vector_callable_symbolic_dense'> sage: vx = v(y=0); vx (x,x) sage: type(vx) <class 'sage.modules.vector_symbolic_dense.Vector_symbolic_dense'>
Work-around
This isn't so bad since we can still do:
sage: v(x, y) = [x+y, x-y] sage: vx = v(y=0)
Now, if every entry still has a variable everything, including positional rather than named arguments, works.
sage: v(x, y) = [x+y, x-y] sage: vx = v(y=0) sage: vx(x=1) (1, 1) sage: vx(1) #deprecated, but works fine
However, things break if taking a section kills off all variables in any component we try to use positional arguments:
sage: v(x, y) = [x+y, x-y] sage: vy = v(y=x) sage: vy (2*x, 0) sage: vx (x, x) sage: vy(x=1) #named arguments still work (2, 0) sage: vy(1) #positional arguments don't ValueError
Change History (6)
comment:1 Changed 9 years ago by
- Description modified (diff)
comment:2 Changed 9 years ago by
- Description modified (diff)
comment:3 Changed 8 years ago by
- Milestone changed from sage-5.11 to sage-5.12
comment:4 Changed 7 years ago by
- Milestone changed from sage-6.1 to sage-6.2
comment:5 Changed 7 years ago by
- Milestone changed from sage-6.2 to sage-6.3
comment:6 Changed 7 years ago by
- Milestone changed from sage-6.3 to sage-6.4