From octave-maintainers-request at bevo dot che dot wisc dot edu  Mon Sep  4 07:23:40 2000
Subject: [PATCH] Add min/max tests. (4/4)
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: Edward Jason Riedy <ejr at EECS dot Berkeley dot EDU>
Cc: octave-maintainers at bevo dot che dot wisc dot edu
Date: Mon, 4 Sep 2000 07:24:12 -0500 (CDT)

On  3-Sep-2000, Edward Jason Riedy <ejr at EECS dot Berkeley dot EDU> wrote:

| This adds a bunch of regression test cases for the previous code.
| It also adds one more that checks that the same comparison is used
| throughout a complex matrix.  Previously, Octave would magically
| revert back to the real comparison (directed rather than magnitude)
| if a column contained only real numbers.  That's surprising.

I think that

  octave:4> x = [1+i, -2; -1+i, 1]
  x =

     1 + 1i  -2 + 0i
    -1 + 1i   1 + 0i

  octave:5> min(x)
  ans =

    -1 + 1i  -2 + 0i

is much less surprising than

  octave:5> min(x)
  ans =

    -1 + 1i   1 + 0i

since -2 is smaller than 1 but I can also see the case for not
applying special cases like this.  (Instead, Octave should perform
data type conversions when appropriate so that the special cases are
not necessary, but that's not possible here since matrices can only be
real or complex, not both.)

How hard would it be to allow either behavior (given an option to min/max)?

jwe