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matrixstata
Serge Garcia
Serge Garcia

Reputation: 11

Stata - Max value in a matrix

I am looking for the appropriate syntax for extracting the maximum value from a matrix and storing it in a local variable for a traditional Stata .do file program.

For example, in the matrix: 

matrix X = (1,2,3 \4,5,6\7,8,9)

the function should return the number 9.

I have looked in the Mata manual and found reference to the colmax, colmin and max functions for Mata, but I can't seem to get them to work.

Upvotes: 1

Views: 2560

Answers (1)

Nick Cox
Nick Cox

Reputation: 37358

You should show attempts at code and what happened to get constructive advice on what you are doing wrong.

Consider 

. mata: max((1,2\3,4))
  4

. mat x = (1,2\3,4)

. mata : max(st_matrix("x"))
  4

. mata: st_local("max", strofreal(max(st_matrix("x"))))

. di `max'
4

The term "local variable" is alien to Stata; a variable is a variable (column) in a dataset (only). The standard term is "local macro". Naturally, in many other languages, such an entity would be regarded as a variable.

Passing a maximum back to Stata as a numeric scalar would often be a better idea. Conversely, what you're most likely to be missing is that strictly a local macro is a string and so you must return its value as a string.

Upvotes: 1

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