How does one perform the exp() operation element-wise in Juila?

Question

I'm new to Julia and this seems like a straight-forward operation but for some reason I am not finding the answer anywhere.

I have been going through some tutorials online and they simply use exp(A) where A is a nxm matrix but this gives me a DimensionMismatch error.

I looked through the documentation on the official website in the elementary functions as well as the linear algebra section and googled it multiple times but can't find it for the life of me.

score 14 · Accepted Answer · answered Dec 08 '19 at 04:41

14

In julia, operations on matrices treat the matrix as an object rather than a collection of numbers. As such exp(A) tries to perform the matrix exponential which is only defined for square matrices. To get element-wise operations on matrices, you use broadcasting which is done with the dot operator. Thus here, you want exp.(A).

This design is used because it allows any scalar operation to be done on arrays rather than just the ones built in to the language.

answered Dec 08 '19 at 04:41

Oscar Smith

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I keep gettting the following error when I try this: `ERROR: MethodError: no method matching exp(::Vector{Int64})` What is going on? – seeker_after_truth Oct 24 '22 at 15:39
what's your code? presumably you need `exp.` somewhere where you have `exp` – Oscar Smith Oct 24 '22 at 16:06

score 9 · Answer 2 · answered Dec 08 '19 at 04:41

9

The broadcasting operator . always changes a function to "element-wise". Therefore the answer is exp.(A), just like sin.(A), cos.(A), or f.(A) for any user-defined f.

answered Dec 08 '19 at 04:41

Chris Rackauckas

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score 2 · Answer 3 · answered Dec 09 '19 at 12:17

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In addition to the above answer, one might also wish to consider the broadcast operator with function piping:

A = rand(-10:10, 3, 3)

A .|> sin .|> inv

answered Dec 09 '19 at 12:17

Meow

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How does one perform the exp() operation element-wise in Juila?

3 Answers3