Fortran versions of some Matlab functions

[rweed]

Recently, I needed to translate some Matlab code to Fortran. To get things to work the same as Matlab I had to create my own versions of the following functions.

1. unique - find unique values in an array
2. mean and standard deviations (mean, std)
3. ismember

Although the code to implement these in Fortran is not complicated for rank 1 and rank 2 arrays it gets complicated for anything greater so it would be nice if there where intrinsic Fortran equivalents

I'm guessing others might have additional functions they would add to this list. When it comes to intrinsics for manipulating and creating arrays along with some other functions, I would be happy if Fortran became Matlabs older but still faster and smarter brother.

[milancurcic]

These look like good candidates for https://github.com/fortran-lang/stdlib.

[certik]

@rweed can you create issues at the stdlib repo please? These would fit well. See e.g.: fortran-lang/stdlib#16, fortran-lang/stdlib#17, fortran-lang/stdlib#18 for similar ideas.