NAME

       units-filter - is a parser for physical and chemical quantities

SYNOPSIS

       units-filter -s  -o  -l

DESCRIPTION

       units-filter is a basic standalone parser written in C language, flex and bison. It inputs
       strings like "1.5e3 nN.m.s^-1" (it could be the time growth ratio of a torque) and outputs
       the value in standard SI unit, followed by the physical dimension of this value.

OPTIONS

       -s
           Like Significant.

           Takes in account the number of significant digits. For example 1.0 m contains 2
           significant digits, while 0.00100 contains 3 significant digits. It is possible to
           enforce the number of significant digits by using a special syntax : if units-filter
           parses the input "1.0m#6", it interprets it as a value with exactly 6 significant
           digits, like "1.00000 m". The number following the # sign is the forced number of
           significant digits. The number of significant digits appears just before the last zero
           in the output of the command (this zero is a placeholder for future extensions).

       -o
           Like Output.

           Outputs a correct representation of the physical quantity with its physical unit in
           the International System notation. There may be some simplification with usual units.
           For example, a newton will be represented by the unit N in place of m.kg.s^-2. The
           value is expressed as a floating number with one digit before the decimal point, and
           as many digits in the mantissa as necessary to fit the desired number of significant
           digits (see an example below). It is possible to enforce the output unit : just add a
           colon and the desired unit at the end of the input. If this unit is homogeneous with
           the former one, it will be used to format the output.

       -l
           Like LaTeX.

           Outputs a correct representation of the physical quantity with its physical unit in
           the International System notation, in LaTeX language.

EXAMPLES

       Establish the SI value and unit exponent of a quantity in the mksa system:

       ~$ echo 1.5e3 nN.m.s^-1 | units-filter

       1.5e-6 2 1 -3 0 0 0 0

       which means : 1.5e-6 (SI unit) m^2.kg.s^-3

       Compare different physical quantities:

       ~$ e1=$(echo "1.2e-3 V" | units-filter)

       ~$ e2=$(echo "1200e3 nWb/s"| units-filter)

       ~$ if [ "$e1" = "$e2" ]; then echo ok; else echo ko; fi

       ok

       ... which emphasizes that webers by unit time are the same as volts.

       Playing with the number of significant digits:

       ~$ echo "0.00100m" | src/units-filter -s

       0.001 1 0 0 0 0 0 0 3 0

       ~$ echo "0.00100m #2" | src/units-filter -s

       0.001 1 0 0 0 0 0 0 2 0

       Giving a value for the relative precision:

       ~$ echo "1kV~2" | units-filter -o

       1e+03 V +-2%

       Turning on the LaTeX output:

       ~$ echo "1kohm+-2%" | units-filter -l

       1\times 10^{+03}\, \Omega \pm 2\,\%

       Turning on the output of a canonical physical notation:

       ~$ echo "1.0 m.kg.s^-2 #7" | units-filter -o

       1.000000e+00N

       Choosing a non-standard unit for the output:

       ~$ echo 1800C:A.h| units-filter -o

       5.000e-01 A.h

KNOWN BUGS

       Few units out of the mksa system are successfully parsed.

AUTHOR

       Georges Khaznadar <georgesk@ofset.org>
           Wrote this manpage.

COPYRIGHT

       Copyright © 2009 Georges Khaznadar

       Permission is granted to copy, distribute and/or modify this document under the terms of
       the GNU General Public License, Version 2 or (at your option) any later version published
       by the Free Software Foundation.

       On Debian systems, the complete text of the GNU General Public License can be found in
       /usr/share/common-licenses/GPL.