Ticket #11848(closed enhancement: fixed)

Opened 20 months ago

Last modified 20 months ago

zero_at() method for RDF/CDF vectors

Reported by: Owned by: rbeezer jason, was minor sage-4.7.2 linear algebra leif N/A Leif Leonhardy Rob Beezer sage-4.7.2.alpha3

Description (last modified by leif) (diff)

This patch adds a method to replace small entries of a floating-point vector with zeros, according to a provided tolerance. It mirrors the matrix method of the same name.

Apply only trac_11848-zero-at-vectors-v2.patch to the Sage library.

Change History

comment:1 Changed 20 months ago by rbeezer

• Cc leif added; lief removed
• Status changed from new to needs_review
• Authors set to Rob Beezer

comment:2 follow-up: ↓ 3 Changed 20 months ago by leif

```if
s/complex matrices/complex vectors/
s/imaginaryparts/imaginary parts/
then
ok
```

(Not yet tested, will do shortly...)

comment:3 in reply to: ↑ 2 ; follow-up: ↓ 4 Changed 20 months ago by rbeezer

Replying to leif:

Thanks for the editorial work. ;-) v2 patch includes indicated changes.

comment:4 in reply to: ↑ 3 Changed 20 months ago by leif

• Reviewers set to Leif Leonhardy
• Description modified (diff)

Replying to rbeezer:

Replying to leif:

Thanks for the editorial work. ;-) v2 patch includes indicated changes.

Yep, immediately seen it. :)

comment:5 Changed 20 months ago by leif

• Status changed from needs_review to positive_review

This function is (e.g.) required by a doctest fix for #7852:

• sage/misc/preparser.py

`diff --git a/sage/misc/preparser.py b/sage/misc/preparser.py`
 a sage: A = matrix(RDF, 5, 5, 2) sage: b = vector(RDF, 5, range(5)) sage: A \ b sage: # On at least one platform, we get a "negative zero": sage: v = A \ b sage: v.zero_at(1e-19) (0.0, 0.5, 1.0, 1.5, 2.0) sage: A._backslash_(b) sage: v = A._backslash_(b) sage: v.zero_at(1e-19) (0.0, 0.5, 1.0, 1.5, 2.0) sage: A * BackslashOperator() * b sage: v = A * BackslashOperator() * b sage: v.zero_at(1e-19) (0.0, 0.5, 1.0, 1.5, 2.0) """ return self.left._backslash_(right)

With both patches applied, the tests now pass on the Skynet machine "cleo" (Linux IA64 / Itanium 2), where they previously failed, so positive review.

comment:6 Changed 20 months ago by leif

• Status changed from positive_review to closed
• Resolution set to fixed
• Merged in set to sage-4.7.2.alpha3

comment:7 Changed 20 months ago by leif

Now also used in sage/matrix/matrix_double_dense.pyx, to fix another doctest error introduced by #7852 (noisy zero in a vector result).

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