Advice on math modules or functions for very long numbers
Following is a very simple program. I am trying to take the 9th root of a number (m), display it, and then recalculate it using the root value that was displayed. As can be seen in the variables 'm' and 'a' there is a difference of 4. My question is two fold: 1) How can I do this in Perl and get correct numbers? and, 2) If this requires a module, which one is it? I may end up using even longer numbers, perhaps up to 20 or 30 digits. It is likely that all numbers ($m) will be integers. $m = 619175052916346; #$m = 27; print "m $m\n"; $r = $m ** (1/9); print "r $r\n"; $a = 44.0083238414736; $b = $a ** 9; print "a $b\n"; Output... m 619175052916346 r 44.0083238414736 a 619175052916350 Thank you, ...Robert Vaughn, Albuquerque, NM ___ ActivePerl mailing list ActivePerl@listserv.ActiveState.com To unsubscribe: http://listserv.ActiveState.com/mailman/mysubs
Regular Expression question w/ long numbers
I am trying to do some simple regular expressions but just can't get them right. I have a very long number that I am trying to perform some reg ex funtions on. When I put the long number in quotes, the reg ex works fine. When I do ot use quotes, the number is viewed as numeric and the reg ex pulls out the scientific notation. These are numbers and not strings. How do I use the reg ex and get the proper numeric information? I am familiar with Math::BigFloat but have not found a solution to my problem within that module. It seems like a simpler question would be; how do I tell Perl to not convert my long numbers to scientific notation? BTW I am using Active State v5.8.7 on Windows XP. Following are code/output samples. Example 1: ## Grab the last three digits after decimal\n"; $m = "7191750529163469.123"; # notice the double quotes, this is now a string print "$m\n"; $m =~ /(\d\d\d)$/; #Get the last three digits. print "$1\n"; Output: 7191750529163469.123123 (this is what I wanted the reg ex to pull out) Example 2: ## Grab the last three digits after decimal\n"; $m = 7191750529163469.123; # notice NO double quotes, this is still a number print "$m\n"; $m =~ /(\d\d\d)$/; #Get the last three digits. print "$1\n"; Output: 7.19175052916347e+015015 (this is NOT what I wanted the reg ex to pull out) ___ ActivePerl mailing list ActivePerl@listserv.ActiveState.com To unsubscribe: http://listserv.ActiveState.com/mailman/mysubs
Re: Regular Expression question w/ long numbers
Thanks! This is what I'm looking for.
-- Original message -- From: "DePriest, Jason R." <[EMAIL PROTECTED]> > use Math::BigFloat; > $m = Math::BigFloat->new('7191750529163469.123'); # notice NO double > quotes, this is still a number > print "$m\n"; > $m =~ /(\d\d\d)$/; #Get the last three digits. > print "$1\n"; > > This gives: > 7191750529163469.123 > 123 > > which is what you are looking for I think. > > -Jason > > On 1/9/06, [EMAIL PROTECTED] <> wrote: > > > > I am trying to do some simple regular expressions but just can't get them > > right. > > > > I have a very long number that I am trying to perform some reg ex funtions > > on. When I put the long number in quotes, the reg ex works fine. When I do > > ot use quotes, the number is viewed as numeric and the reg ex pulls out the > > scientific notation. > > > > These are numbers and not strings. How do I use the reg ex and get the > > proper numeric information? I am familiar with Math::BigFloat but have not > > found a solution to my problem within that module. > > > > It seems like a simpler question would be; how do I tell Perl to not convert > > my long numbers to scientific notation? > > > > BTW I am using Active State v5.8.7 on Windows XP. > > > > Following are code/output samples. > > > > Example 1: > > ## Grab the last three digits after decimal\n"; > > $m = "7191750529163469.123"; # notice the double quotes, this is now a > > string > > print "$m\n"; > > $m =~ /(\d\d\d)$/; #Get the last three digits. > > p!
rint "$1\n"; > > > > Output: > > 7191750
529163469.123 > > 123 (this is what I wanted the reg ex to pull out) > > > > Example 2: > > ## Grab the last three digits after decimal\n"; > > $m = 7191750529163469.123; # notice NO double quotes, this is still a > > number > > print "$m\n"; > > $m =~ /(\d\d\d)$/; #Get the last three digits. > > print "$1\n"; > > > > Output: > > 7.19175052916347e+015 > > 015 (this is NOT what I wanted the reg ex to pull out) > > ___ > > ActivePerl mailing list > > ActivePerl@listserv.ActiveState.com > > To unsubscribe: > > http://listserv.ActiveState.com/mailman/mysubs > > > > > > ___ > ActivePerl mailing list > ActivePerl@listserv.ActiveState.com > To unsubscribe: http://l!
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Re: Regular Expression question w/ long numbers
Thanks for the feedback. I am studying prime factorization of very large numbers. In particular, I am working on tests that work in the inverse of prime factorization. In that, I mean that I am actually testing for composite numbers. What is quicker; to determine if a number is prime or composite? I need an extreme level of precision because rounding invalidates the protocols within which I can correctly calculate. I'm using Perl because I can look at a number as a string, parse it at different points and more easily explore a variey of number theories. Thank you, ...Robert Vaughn, Albuquerque, NM -- Original message -- From: David Nicol <[EMAIL PROTECTED]> > On 1/9/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]>wrote: > > > It seems like a simpler question would be; how do I tell Perl to not convert > > my long numbers to scientific notation? > > keep them as strings, as you are doing. Why do you need such accuracy? > What process is generating real data that you are measuring to nineteen > digits of accuracy? > > Your so-called numbers might be better dealt with as entirely as strings. ___ ActivePerl mailing list ActivePerl@listserv.ActiveState.com To unsubscribe: http://listserv.ActiveState.com/mailman/mysubs
