document that inv(x) is not just for matrices #22610
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
tkelman
reviewed
Jun 29, 2017
base/number.jl
Outdated
| some types `inv(x)` may be slightly more efficient. | ||
|
|
||
| # Examples | ||
|
|
ararslan
approved these changes
Jun 29, 2017
musm
reviewed
Jun 30, 2017
base/number.jl
Outdated
| inv(x) | ||
|
|
||
| Return the multiplicative inverse of `x`, such that `x*inv(x)` or `inv(x)*x` | ||
| yields [`one(x)`](@ref) (the multiplicative identity). |
There was a problem hiding this comment.
As @MikaelSlevinsky mentioned this isn't true. i.e. x*inv(x) or inv(x)*x does not yield one(x)
julia> x=49.0
julia> inv(x)*x
0.9999999999999999
julia> one(x)
1.0
There was a problem hiding this comment.
Not sure on the best way to word this but probably best to write essentially yields instead of yields or something alike that doesn't imply inv(x)*x == one(x)
musm
reviewed
Jun 30, 2017
base/number.jl
Outdated
| Return the multiplicative inverse of `x`, such that `x*inv(x)` or `inv(x)*x` | ||
| yields [`one(x)`](@ref) (the multiplicative identity). | ||
|
|
||
| If `x` is a number, this is essentially the same as `one(x)/x`, but for |
There was a problem hiding this comment.
It need not be identical under roundoff errors, nor is it necessarily computationally identical. Hence "essentially"
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
inv(x)returns the multiplicative identity for anyx, not just matrices, but this wasn't documented.(See comments at JuliaMath/SpecialFunctions.jl#32.)