infinity

How do I create or test for NaN or infinite values in Perl? print "Is NaN\n" if $a eq 'nan'; print "Is Inf\n" if $a eq 'inf' or $a eq '-inf'; EDIT : Fixed for negative infinity. ysth Here's a fairly reliable way: my $inf = 9**9**9; my $neginf = -9**9**9; my $nan = -sin(9**9**9); sub isinf { $_[0]==9**9**9 || $_[0]==-9**9**9 } sub isnan { ! defined( $_[0] <=> 9**9**9 ) } # useful for detecting negative zero sub signbit { substr( sprintf( '%g', $_[0] ), 0, 1 ) eq '-' } for my $num ( $inf, $neginf, $nan ) { printf("%s:\tisinf: %d,\tisnan: %d,\tsignbit: %d\n", $num, isinf($num), isnan($num),

I use ANSI C89 (not C++), and I want to generate NaN, -Infinity and +Infinity. Is there any standard way (eg. standard macro)? Or is there any platform and compiler independent way to generate these numbers? float f = 0.0 / 0.0; // Is f ALWAYS in any platform is NaN? There is in C99, but not in previous standards AFAIK. In C99, you'll have NAN and INFINITY macros. From "Mathematics <math.h> " (§7.12) section The macro INFINITY expands to a constant expression of type float representing positive or unsigned infinity, if available; ... If you're stuck with ANSI C89, you're out of luck. See C-FAQ

So Python has positive and negative infinity: float("inf"), float("-inf") This just seems like the type of feature that has to have some caveat. Is there anything I should be aware of? You can still get not-a-number (NaN) values from simple arithmetic involving inf : >>> 0 * float("inf") nan Note that you will normally not get an inf value through usual arithmetic calculations: >>> 2.0**2 4.0 >>> _**2 16.0 >>> _**2 256.0 >>> _**2 65536.0 >>> _**2 4294967296.0 >>> _**2 1.8446744073709552e+19 >>> _**2 3.4028236692093846e+38 >>> _**2 1.157920892373162e+77 >>> _**2 1.3407807929942597e+154 >>> _**2

How can I represent an infinite number in python? No matter which number you enter in the program, no number should be greater than this representation of infinity. In Python, you can do: test = float("inf") In Python 3.5, you can do: import math test = math.inf And then: test > 1 test > 10000 test > x Will always be true. Unless of course, as pointed out, x is also infinity or "nan" ("not a number"). Additionally (Python 2.x ONLY), in a comparison to Ellipsis , float(inf) is lesser, e.g: float('inf') < Ellipsis would return true. Since Python 3.5 you can use math.inf : >>> import math >>>

I have JavaScript Object say: var a = {b: Infinity, c: 10}; When I do var b = JSON.stringify(a); it returns the following b = "{"b":null, "c":10}"; How is the JSON.stringify converts the object to strings? I tried MDN Solution . function censor(key, value) { if (value == Infinity) { return "Infinity"; } return value; } var b = JSON.stringify(a, censor); But in this case I have to return the string "Infinity" not Infinity . If I return Infinity it again converts Infinity to null. How do I solve this problem. Like the other answers stated, Infintity is not part of the values JSON can store as

Does Java have anything to represent infinity for every numerical data type? How is it implemented such that I can do mathematical operations with it? E.g. int myInf = infinity; //However it is done myInf + 5; //returns infinity myInf*(-1); //returns negative infinity I have tried using very large numbers, but I want a proper, easy solution. double supports Infinity double inf = Double.POSITIVE_INFINITY; System.out.println(inf + 5); System.out.println(inf - inf); // same as Double.NaN System.out.println(inf * -1); // same as Double.NEGATIVE_INFINITY prints Infinity NaN -Infinity note: Infinity