-
-
Notifications
You must be signed in to change notification settings - Fork 5.4k
/
sign.c
40 lines (38 loc) · 1.11 KB
/
sign.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
/*
* Mathlib : A C Library of Special Functions
* Copyright (C) 1998 Ross Ihaka
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, a copy is available at
* http:https://www.r-project.org/Licenses/
*
* SYNOPSIS
*
* #include <Rmath.h>
* double sign(double x);
*
* DESCRIPTION
*
* This function computes the 'signum(.)' function:
*
* sign(x) = 1 if x > 0
* sign(x) = 0 if x == 0
* sign(x) = -1 if x < 0
*/
#include "nmath.h"
double sign(double x)
{
if (ISNAN(x))
return x;
return ((x > 0) ? 1 : ((x == 0)? 0 : -1));
}