Feature #14116: Add Matrix #exponentiate method as Matlab's exp

• Status: Feedback
• Priority: Normal
• Assignee: marcandre (Marc-Andre Lafortune)
• Target version: -

[greggzst (Grzegorz Jakubiak)]

Add exponentiate method which results in returning a new matrix with each element being an exponent of the number e.
Here is PR for that: https://github.com/ruby/ruby/pull/1762

[greggzst (Grzegorz Jakubiak)]

• Description updated (diff)

[greggzst (Grzegorz Jakubiak)]

• Subject changed from Add Matrix #exponentiate method to Add Matrix #exponentiate method as Matlab's exp

[marcandre (Marc-Andre Lafortune)]

• Status changed from Open to Feedback
• Assignee set to marcandre (Marc-Andre Lafortune)

Thanks for the PR.

The name is not acceptable, as the exponential of a matrix is something different (expm in Matlab): https://en.wikipedia.org/wiki/Matrix_exponential

I wish I was more familiar with machine learning to know how frequent calculating this is. If it is, there should be a name for this, no?

The fact that map{|e| Math.exp(e)} is quite simple to do makes me even more hesitant to add that method too.

[MSP-Greg (Greg L)]

marcandre (Marc-Andre Lafortune) wrote:

Thanks for the PR.

The name is not acceptable, as the exponential of a matrix is something different

I agree. Not quite a single line method. Maybe something like entrywise_exp or entrywise_exponential like in 60860. But as you mentioned, 'is quite simple'...

[shevegen (Robert A. Heiler)]

Once again it is back to the oldest problem in computer technology - giving things a proper name. :-)

[greggzst (Grzegorz Jakubiak)]

marcandre (Marc-Andre Lafortune) wrote:

Thanks for the PR.

The name is not acceptable, as the exponential of a matrix is something different (expm in Matlab): https://en.wikipedia.org/wiki/Matrix_exponential

I wish I was more familiar with machine learning to know how frequent calculating this is. If it is, there should be a name for this, no?

The fact that map{|e| Math.exp(e)} is quite simple to do makes me even more hesitant to add that method too.

I changed the name to entrywise_exp as suggested. True about the simplicity but it would be a good shorthand taking into consideration fact that it is used in many cases e.g. multivariate normal distribution.