Script for finding standard deviation


 
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Old 09-11-2008
Jim, thanks for all your help.
Here is the final awk code I am using. It is subject to rounding errors but it is close enough for my needs.

Code:
 
awk -F','  '{ sum=0; sumsq=0;
for(i=1; i<=NF;i++) {sum+=$i; sumsq+=$i*$i} 
printf("sumsq=%f  sum=%f  mean=%f  stddev= %f\n",sumsq, sum, sum/NF, sqrt((sumsq-(NF*((sum/NF))*(sum/NF)))/NF) ) } ' test

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math(n) 							 Tcl Math Library							   math(n)

__________________________________________________________________________________________________________________________________________________

NAME
math - Tcl Math Library SYNOPSIS
package require Tcl 8.2 package require math ?1.2.4? ::math::cov value value ?value ...? ::math::integrate list of xy value pairs ::math::fibonacci n ::math::max value ?value ...? ::math::mean value ?value ...? ::math::min value ?value ...? ::math::product value ?value ...? ::math::random ?value1? ?value2? ::math::sigma value value ?value ...? ::math::stats value value ?value ...? ::math::sum value ?value ...? _________________________________________________________________ DESCRIPTION
The math package provides utility math functions. Besides a set of basic commands, available via the package math, there are more specialised packages: o math::bigfloat - Arbitrary-precision floating-point arithmetic o math::bignum - Arbitrary-precision integer arithmetic o math::calculus::romberg - Robust integration methods for functions of one variable, using Romberg integration o math::calculus - Integration of functions, solving ordinary differential equations o math::combinatorics - Procedures for various combinatorial functions (for instance the Gamma function and "k out of n") o math::complexnumbers - Complex number arithmetic o math::constants - A set of well-known mathematical constants, such as Pi, E, and the golden ratio o math::fourier - Discrete Fourier transforms o math::fuzzy - Fuzzy comparisons of floating-point numbers o math::geometry - 2D geometrical computations o math::interpolate - Various interpolation methods o math::linearalgebra - Linear algebra package o math::optimize - Optimization methods o math::polynomials - Polynomial arithmetic (includes families of classical polynomials) o math::rationalfunctions - Arithmetic of rational functions o math::roman - Manipulation (including arithmetic) of Roman numerals o math::special - Approximations of special functions from mathematical physics o math::statistics - Statistical operations and tests BASIC COMMANDS
::math::cov value value ?value ...? Return the coefficient of variation expressed as percent of two or more numeric values. ::math::integrate list of xy value pairs Return the area under a "curve" defined by a set of x,y pairs and the error bound as a list. ::math::fibonacci n Return the n'th Fibonacci number. ::math::max value ?value ...? Return the maximum of one or more numeric values. ::math::mean value ?value ...? Return the mean, or "average" of one or more numeric values. ::math::min value ?value ...? Return the minimum of one or more numeric values. ::math::product value ?value ...? Return the product of one or more numeric values. ::math::random ?value1? ?value2? Return a random number. If no arguments are given, the number is a floating point value between 0 and 1. If one argument is given, the number is an integer value between 0 and value1. If two arguments are given, the number is an integer value between value1 and value2. ::math::sigma value value ?value ...? Return the population standard deviation of two or more numeric values. ::math::stats value value ?value ...? Return the mean, standard deviation, and coefficient of variation (as percent) as a list. ::math::sum value ?value ...? Return the sum of one or more numeric values. BUGS, IDEAS, FEEDBACK This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category math of the Tcllib SF Trackers [http://sourceforge.net/tracker/?group_id=12883]. Please also report any ideas for enhancements you may have for either package and/or documentation. KEYWORDS
math, statistics math 1.2.4 math(n)