PI day. Post: 303014677

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Operating Systems OS X (Apple) PI day. Post 303014677 by wisecracker on Sunday 18th of March 2018 06:45:02 AM

03-18-2018

Registered User

PI day.

Hi guys and gals...
OSX 10.13.3, default bash terminal calling ksh in the code.
I decided to have a go at creating PI using ksh only as a bit of fun.
I also decided on a Taylor series to do such a task.
This was the fun bit of code that generates PI to 6 decimal places although it could easily be set to continuous running and calculate within the limits of ksh's floating point precision.
It takes around 35 seconds to calculate to six decimal places...

Code:

#!/bin/ksh
# !/usr/local/bin/dash
# PI using the Taylor series.
# PI/4 = 1 - 1/3 + 1/5 - 1/7 + 1/9 - 1/11......

clear
OP="-"
BASE=3.0
VAL=1.0
N=1
MYPI=0.0
while true
do
	if [ $(( $N % 2 )) -eq 0 ]
	then
		OP="+"
	fi
	if [ $(( $N % 2 )) -gt 0 ]
	then
		OP="-"
	fi
	VAL=$(( ($VAL * 1.0) $OP (1.0 / $BASE) ))
	BASE=$(( $BASE + 2.0 ))
	N=$(( $N + 1 ))
	MYPI=$(( $VAL * 4.0 ))
	# Hard coded known value to exit loop without interaction.
	if [ "${MYPI:0:8}" == "3.141592" ]
	then
		break
	fi
done
printf "PI to six decimal places = %.6f...\nIterations = $N...\n" "$MYPI"

Result:

Code:

PI to six decimal places = 3.141592...
Iterations = 1530012...
AMIGA:amiga~/Desktop/Code/Shell> _

Enjoy and hope to see other solutions on this thread...

Last edited by wisecracker; 03-18-2018 at 07:54 AM..

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LEARN ABOUT SUNOS

shells

shells(4)							   File Formats 							 shells(4)

NAME

       shells - shell database

SYNOPSIS

       /etc/shells

DESCRIPTION

       The shells file contains a list of the shells on the system. Applications use this file to determine whether a shell is valid. See getuser-
       shell(3C). For each shell a single line should be present, consisting of the shell's path, relative to root.

       A hash mark (#) indicates the beginning of a comment; subsequent characters up to the end of the line are not interpreted by  the  routines
       which search the file. Blank lines are also ignored.

       The  following  default	shells are used by utilities: /bin/bash, /bin/csh, /bin/jsh, /bin/ksh, /bin/pfcsh, /bin/pfksh, /bin/pfsh, /bin/sh,
       /bin/tcsh,  /bin/zsh,  /sbin/jsh,  /sbin/sh,  /usr/bin/bash,  /usr/bin/csh,  /usr/bin/jsh,  /usr/bin/ksh,  /usr/bin/pfcsh,  /usr/bin/pfksh,
       /usr/bin/pfsh, and /usr/bin/sh, /usr/bin/tcsh, /usr/bin/zsh. Note that /etc/shells overrides the default list.

       Invalid shells in /etc/shells may cause unexpected behavior (such as being unable to log in by way of ftp(1)).

FILES

       /etc/shells	       lists shells on system

SEE ALSO

       vipw(1B), ftpd(1M), sendmail(1M), getusershell(3C), aliases(4)

SunOS 5.10							    4 Jun 2001								 shells(4)