* [ruby-core:75394] [Ruby trunk Bug#12356] Vector covector incorrect multiplication with another vector.
[not found] <redmine.issue-12356.20160506235154@ruby-lang.org>
@ 2016-05-06 23:51 ` rafael.soares81
2019-08-23 22:35 ` [ruby-core:94513] [Ruby master " merch-redmine
2019-08-26 14:54 ` [ruby-core:94568] " ruby-core
2 siblings, 0 replies; 3+ messages in thread
From: rafael.soares81 @ 2016-05-06 23:51 UTC (permalink / raw)
To: ruby-core
Issue #12356 has been reported by Rafael Silva.
----------------------------------------
Bug #12356: Vector covector incorrect multiplication with another vector.
https://bugs.ruby-lang.org/issues/12356
* Author: Rafael Silva
* Status: Open
* Priority: Normal
* Assignee:
* ruby -v: ruby 2.2.4p230 (2015-12-16 revision 53155) [x86_64-linux]
* Backport: 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN
----------------------------------------
Version 2.2.4
v1 = Vector[2,3,4]
v2 = Vector[4,5,6]
v1.covector.row_size #1
v1.covector.column_size #3
v2.covector.row_size #1
v2.covector.column_size #3
Vector does not have distinction between row and column, there's no column vector notion in the language.
v1 * v2.covector #Matrix[[8,10,12],[12,15,18],[16,20,24]]
# Should be illegal. But works like if v2.covector is transposed / column vector which it's clearly not.
v1.covector * v2.covector #ExceptionForMatrix::ErrDimensionMismatch: Matrix dimension mismatch
# Expected
v1 * v2 #ExceptionForMatrix::ErrOperationNotDefined: Operation(*) can't be defined: Vector op Vector
# No comments, see my observation below.
v1.covector * v2 #Vector[47]
#Again covector treated like transposed / column vector.
Personal observation: Terrible choice to represent Vector like an Array, Vector should be a shortcut to Matrix.
--
https://bugs.ruby-lang.org/
^ permalink raw reply [flat|nested] 3+ messages in thread
* [ruby-core:94513] [Ruby master Bug#12356] Vector covector incorrect multiplication with another vector.
[not found] <redmine.issue-12356.20160506235154@ruby-lang.org>
2016-05-06 23:51 ` [ruby-core:75394] [Ruby trunk Bug#12356] Vector covector incorrect multiplication with another vector rafael.soares81
@ 2019-08-23 22:35 ` merch-redmine
2019-08-26 14:54 ` [ruby-core:94568] " ruby-core
2 siblings, 0 replies; 3+ messages in thread
From: merch-redmine @ 2019-08-23 22:35 UTC (permalink / raw)
To: ruby-core
Issue #12356 has been updated by jeremyevans0 (Jeremy Evans).
Assignee set to marcandre (Marc-Andre Lafortune)
Status changed from Open to Assigned
I don't think this is a bug, but I'll let marcandre make the determination. `Vector` can't be multipled with `Vector`, you get an error. You can multiple a `Vector` by a `Matrix` and vice-versa by design, and `Vector#covector` returns a `Matrix`. You can multiple a `Matrix` by a `Matrix` only if the column_count of the receiver is the row count of the argument.
Whether `Vector` is good design or bad design I'm not going to speculate on. However, you could consider using NMatrix (https://rubygems.org/gems/nmatrix), as that represents vectors as matrices.
----------------------------------------
Bug #12356: Vector covector incorrect multiplication with another vector.
https://bugs.ruby-lang.org/issues/12356#change-80949
* Author: edmorte (Rafael Silva)
* Status: Assigned
* Priority: Normal
* Assignee: marcandre (Marc-Andre Lafortune)
* Target version:
* ruby -v: ruby 2.2.4p230 (2015-12-16 revision 53155) [x86_64-linux]
* Backport: 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN
----------------------------------------
Version 2.2.4
v1 = Vector[2,3,4]
v2 = Vector[4,5,6]
v1.covector.row_size #1
v1.covector.column_size #3
v2.covector.row_size #1
v2.covector.column_size #3
Vector does not have distinction between row and column, there's no column vector notion in the language.
v1 * v2.covector #Matrix[[8,10,12],[12,15,18],[16,20,24]]
# Should be illegal. But works like if v2.covector is transposed / column vector which it's clearly not.
v1.covector * v2.covector #ExceptionForMatrix::ErrDimensionMismatch: Matrix dimension mismatch
# Expected
v1 * v2 #ExceptionForMatrix::ErrOperationNotDefined: Operation(*) can't be defined: Vector op Vector
# No comments, see my observation below.
v1.covector * v2 #Vector[47]
#Again covector treated like transposed / column vector.
Personal observation: Terrible choice to represent Vector like an Array, Vector should be a shortcut to Matrix.
--
https://bugs.ruby-lang.org/
^ permalink raw reply [flat|nested] 3+ messages in thread
* [ruby-core:94568] [Ruby master Bug#12356] Vector covector incorrect multiplication with another vector.
[not found] <redmine.issue-12356.20160506235154@ruby-lang.org>
2016-05-06 23:51 ` [ruby-core:75394] [Ruby trunk Bug#12356] Vector covector incorrect multiplication with another vector rafael.soares81
2019-08-23 22:35 ` [ruby-core:94513] [Ruby master " merch-redmine
@ 2019-08-26 14:54 ` ruby-core
2 siblings, 0 replies; 3+ messages in thread
From: ruby-core @ 2019-08-26 14:54 UTC (permalink / raw)
To: ruby-core
Issue #12356 has been updated by marcandre (Marc-Andre Lafortune).
Status changed from Assigned to Rejected
Thanks Jeremy for updating this issue. I double checked and never received the original email notification...
> `Vector` does not have distinction between row and column, there's no column vector notion in the language.
Actually, in the library `Vector` is a column vector. You can see this for example with:
```
Vector[1, 2].to_matrix # => Matrix[[1], [2]]
```
So I believe that it is correct that `v.covector * v` or `v * v.covector` returns some result while other combinations should raise.
I'll close this but will reopen if there's more discussion to be had.
----------------------------------------
Bug #12356: Vector covector incorrect multiplication with another vector.
https://bugs.ruby-lang.org/issues/12356#change-81025
* Author: edmorte (Rafael Silva)
* Status: Rejected
* Priority: Normal
* Assignee: marcandre (Marc-Andre Lafortune)
* Target version:
* ruby -v: ruby 2.2.4p230 (2015-12-16 revision 53155) [x86_64-linux]
* Backport: 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN
----------------------------------------
Version 2.2.4
v1 = Vector[2,3,4]
v2 = Vector[4,5,6]
v1.covector.row_size #1
v1.covector.column_size #3
v2.covector.row_size #1
v2.covector.column_size #3
Vector does not have distinction between row and column, there's no column vector notion in the language.
v1 * v2.covector #Matrix[[8,10,12],[12,15,18],[16,20,24]]
# Should be illegal. But works like if v2.covector is transposed / column vector which it's clearly not.
v1.covector * v2.covector #ExceptionForMatrix::ErrDimensionMismatch: Matrix dimension mismatch
# Expected
v1 * v2 #ExceptionForMatrix::ErrOperationNotDefined: Operation(*) can't be defined: Vector op Vector
# No comments, see my observation below.
v1.covector * v2 #Vector[47]
#Again covector treated like transposed / column vector.
Personal observation: Terrible choice to represent Vector like an Array, Vector should be a shortcut to Matrix.
--
https://bugs.ruby-lang.org/
^ permalink raw reply [flat|nested] 3+ messages in thread
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2016-05-06 23:51 ` [ruby-core:75394] [Ruby trunk Bug#12356] Vector covector incorrect multiplication with another vector rafael.soares81
2019-08-23 22:35 ` [ruby-core:94513] [Ruby master " merch-redmine
2019-08-26 14:54 ` [ruby-core:94568] " ruby-core
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