annotate Python/hypot.c @ 17405:afbb65b60fa2 2.0

Inspired by Tim Peters' 1.14->1.15 checkin to asynchat Quoting orignal message: ''' Fix from the Madusa mailing list: http://groups.yahoo.com/group/medusa/message/333 It's clear that Medusa should not be checking for an empty buffer via "buf is ''". The patch merely changes "is" to "==". However, there's a mystery here all the same: Python attempts to store null strings uniquely, so it's unclear why "buf is ''" ever returned false when buf actually was empty. *Some* string operations produce non-unique null strings, e.g. '''
author Moshe Zadka <moshez@math.huji.ac.il>
date Wed, 11 Apr 2001 08:06:02 +0000
parents 59f8cedcf049
children 2dea40e40d9d
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
4176
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
1 /* hypot() replacement */
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
2
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
3 #include "config.h"
13761
59f8cedcf049 merge Include/my*.h into Include/pyport.h
Peter Schneider-Kamp <nowonder@nowonder.de>
parents: 13658
diff changeset
4 #include "pyport.h"
4176
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
5
13658
f79434ee41fa Mass ANSIfication of function definitions. Doesn't cover all 'extern'
Thomas Wouters <thomas@python.org>
parents: 4176
diff changeset
6 double hypot(double x, double y)
4176
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
7 {
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
8 double yx;
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
9
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
10 x = fabs(x);
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
11 y = fabs(y);
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
12 if (x < y) {
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
13 double temp = x;
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
14 x = y;
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
15 y = temp;
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
16 }
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
17 if (x == 0.)
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
18 return 0.;
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
19 else {
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
20 yx = y/x;
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
21 return x*sqrt(1.+yx*yx);
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
22 }
37d009b1bf45 *** empty log message ***
Guido van Rossum <guido@python.org>
parents:
diff changeset
23 }