st: double equal sign with -matrix-

 From Jacob Wegelin To statalist@hsphsun2.harvard.edu Subject st: double equal sign with -matrix- Date Wed, 11 Mar 2009 14:15:49 -0400

```Is there any reason why, with  -matrix- , a double equal sign has the
same effect (apparently) as a single equal sign?

The code below demonstrates that the double equal sign, "==", is not
tolerated in an assignment of a value to a scalar---presumably because
it is used as a logical operator to test for equality--but that, with
the -matrix- command, the double equal sign seems to mean the same as
a single equal sign.

. clear all

. matrix input A = (1,2\3,4)

. mat lis A

A[2,2]
c1  c2
r1   1   2
r2   3   4

. mat okay=A

. mat lis okay

okay[2,2]
c1  c2
r1   1   2
r2   3   4

. matrix weird==A

. mat lis weird

weird[2,2]
c1  c2
r1   1   2
r2   3   4

. scalar asExpected==5
varlist not allowed
r(101);

. scalar asExpected=5

Can anyone shed light on this?

Thanks

Jacob A. Wegelin
Assistant Professor
Department of Biostatistics
Virginia Commonwealth University
730 East Broad Street Room 3006
P. O. Box 980032
Richmond VA 23298-0032
U.S.A.
E-mail: jwegelin@vcu.edu

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```