Arithmetic on a Float in bash Post: 302958596

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Top Forums Shell Programming and Scripting Arithmetic on a Float in bash Post 302958596 by prodigious8 on Friday 23rd of October 2015 03:02:26 PM

10-23-2015

Registered User

Arithmetic on a Float in bash

I am using bash
I have a script that takes a number, i.e. 85.152, which is always a non integer and essentially tries to get that number to be a multiple of 10. My code is as follows:

Code:

number=85.152
A=${number%.*} #Converts float to integer
typeset -i B=$(((A-20)/10)) #subtracting 20 is desired, dividing by 10 is done to get the value less than 10 (only works for numbers less than 100)
typeset -i C=${B%.*} #converts float to integer (redundant I know, but necessary)
typeset -i answer=$((C * 10)) #Gives me a multiple of 10

Explanation:
1. I convert from a float to integer first because I cannot simply divide 85.152 by 10 using bash. It does not like dividing floats.
2. I subtract 20 because this is desired by design (it can be ignored). The division by 10 gets me to a number below 10 which is just a trick because any integer less than 10 which is multiplied by 10 will simply be a multiple of 10.
3. I convert from float to integer again just in case the number I divided, (to get less than 10), ends up dividing out to be another float (i.e. 85/10=8.5, then truncate to 8).
4. Finally I multiply by 10, 8*10=80 which is a multiple of 10.

I did what I could as a newbie to make it work but now I would like to simplify this process. I simply want to take 85.152 and make it a multiple of 10 that is 20 less than 85.152. So answer = (85.125-20) truncated to a multiple of 10. Should be 60. Any suggestions?

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LEARN ABOUT HPUX

libbash

LIBBASH(7)							  libbash Manual							LIBBASH(7)

NAME

     libbash -- A bash shared libraries package.

DESCRIPTION

     libbash  is  a package that enables bash dynamic-like shared libraries. Actually its a tool for managing bash scripts whose functions you may
     want to load and use in scripts of your own.

     It contains a 'dynamic loader' for the shared libraries ( ldbash(1)), a configuration tool (ldbashconfig(8)), and some libraries.

     Using ldbash(1) you are able to load loadable bash libraries, such as getopts(1) and hashstash(1).  A bash shared library that can be  loaded
     using
     ldbash(1) must answer 4 requirments:

     1.     It must be installed in $LIBBASH_PREFIX/lib/bash (default is /usr/lib/bash).

     2.     It must contain a line that begins with '#EXPORT='.  That line will contain (after the '=') a list of functions that the library
	    exports.  I.e. all the function that will be usable after loading that library will be listed in that line.

     3.     It must contain a line that begins with '#REQUIRE='.  That line will contain (after the '=') a list of bash libraries that are
	    required for our library.  I.e. every bash library that is in use in our bash library must be listed there.

     4.     The library must be listed (For more information, see ldbashconfig(8)).

   Basic guidelines for writing library of your own:
     1.     Be aware, that your library will be actually sourced. So, basically, it should contain (i.e define) only functions.

     2.     Try to declare all variables intended for internal use as local.

     3.     Global variables and functions that are intended for internal use (i.e are not defined in '#EXPORT=') should begin with:
		  __<library_name>_
	    For example, internal function myfoosort of hashstash library should be named as
		  __hashstash_myfoosort
	    This helps to avoid conflicts in global name space when using libraries that come from different vendors.

     4.     See html manual for full version of this guide.

AUTHORS

     Hai Zaar <haizaar@haizaar.com>
     Gil Ran <ril@ran4.net>

SEE ALSO

     ldbash(1), ldbashconfig(8), getopts(1), hashstash(1) colors(1) messages(1) urlcoding(1) locks(1)

Linux								       Epoch								     Linux

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