Q: Is SQRT(n) possible in a POSIX compliant shell? A: Yes within limits. Post: 303039666

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Top Forums Shell Programming and Scripting Q: Is SQRT(n) possible in a POSIX compliant shell? A: Yes within limits. Post 303039666 by wisecracker on Friday 11th of October 2019 10:51:01 AM

10-11-2019

Registered User

;oDD

I showed it to the wife and I said 'what sticks out the most?'
She said the 'pink obviously!'

Anyhow here is an add-on to get Fixed Point Numbers SQRT from .100 to 9200000.000 using 'sqrt_bash.sh' edited to 32 bit mode.
All entries MUST be Fixed Point values even if they end in ?.000...

Code:

#!/usr/local/bin/dash
# FP_sqrt.sh
#
# Requires sqrt_dash.sh to work.
# This MUST be 3 decimal places only using 'sqrt_bash.sh' in 32 bit mode running in 64 bit.
#
# Usage: [full/path/to/][./]FP_sqrt.sh <.100_to_a_little_over_9200000.000>
#
# Note: numbers below 1.000 the input must be .??? format without the leading zero.
# The errors below .100 grow exponentially so values cannot to be trusted.

NUMBER=${1}

# Step 1, allocate this to _fractional_ part.
FRACT="${NUMBER##*.}"

# Step 2, get _whole_number_ part.
WHOLE="${NUMBER%%.*}"

# Step 3, put WHOLE and FRACT together and include 3 zeros.
NUMBER="${WHOLE}${FRACT}"'000'

# Step 4, call "sqrt_dash.sh" with new NUMBER into a variable.
NUMBER=$( ./sqrt_dash.sh "${NUMBER}" )

printf "%.3f\n" ${NUMBER}e-3

Results, confirmed by Google. Same MBP platform as always.

Code:

Last login: Fri Oct 11 15:15:40 on ttys000
AMIGA:amiga~> cd Desktop/Code/Shell
AMIGA:amiga~/Desktop/Code/Shell> ./FP_sqrt.sh .100
0.316
AMIGA:amiga~/Desktop/Code/Shell> ./FP_sqrt.sh .250
0.500
AMIGA:amiga~/Desktop/Code/Shell> ./FP_sqrt.sh .500
0.707
AMIGA:amiga~/Desktop/Code/Shell> ./FP_sqrt.sh .750
0.866
AMIGA:amiga~/Desktop/Code/Shell> ./FP_sqrt.sh 1.000
1.000
AMIGA:amiga~/Desktop/Code/Shell> ./FP_sqrt.sh 2.000
1.414
AMIGA:amiga~/Desktop/Code/Shell> ./FP_sqrt.sh 20.000
4.472
AMIGA:amiga~/Desktop/Code/Shell> ./FP_sqrt.sh 200.000
14.142
AMIGA:amiga~/Desktop/Code/Shell> ./FP_sqrt.sh 333.333
18.257
AMIGA:amiga~/Desktop/Code/Shell> ./FP_sqrt.sh 777.777
27.889
AMIGA:amiga~/Desktop/Code/Shell> ./FP_sqrt.sh 9187233.598
3031.045
AMIGA:amiga~/Desktop/Code/Shell> _

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sqrtf

SQRT(3) 						     Linux Programmer's Manual							   SQRT(3)

NAME

       sqrt, sqrtf, sqrtl - square root function

SYNOPSIS

       #include <math.h>

       double sqrt(double x);
       float sqrtf(float x);
       long double sqrtl(long double x);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       sqrtf(), sqrtl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or cc -std=c99

DESCRIPTION

       The sqrt() function returns the nonnegative square root of x.

RETURN VALUE

       On success, these functions return the square root of x.

       If x is a NaN, a NaN is returned.

       If x is +0 (-0), +0 (-0) is returned.

       If x is positive infinity, positive infinity is returned.

       If x is less than -0, a domain error occurs, and a NaN is returned.

ERRORS

       See math_error(7) for information on how to determine whether an error has occurred when calling these functions.

       The following errors can occur:

       Domain error: x less than -0
	      errno is set to EDOM.  An invalid floating-point exception (FE_INVALID) is raised.

CONFORMING TO

       C99, POSIX.1-2001.  The variant returning double also conforms to SVr4, 4.3BSD, C89.

SEE ALSO

       cbrt(3), csqrt(3), hypot(3)

COLOPHON

       This  page is part of release 3.25 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

								    2008-08-05								   SQRT(3)