unithelp

Description

Displays description of un (unit conversion structure)

This is a user-defined function from constants.dvrc

Arguments and Return Values

Arguments: None; just enter unithelp()

Return Value: Prints description of each element of structure un when not given any input; returns null for any input(s)

Usage

Syntax: unithelp()

Examples

dv> un
struct, 27 elements
    in: 0.0254000
    ft: 0.304800
    mi: 1609.34
    AU: 1.49598e+11
    ly: 9.46073e+15
    pc: 3.08568e+16
    oz: 0.0283495
    lb: 0.453592
    day: 86400.0
    Jyr: 3.15576e+07
    floz: 2.95735e-05
    L: 0.00100000
    gal: 0.00378541
    mph: 0.447040
    ozf: 0.278014
    lbf: 4.44822
    cal: 4.18400
    tTNT: 4.18400e+09
    hp: 746.000
    mbar: 100.000
    torr: 133.322
    psi: 6894.76
    bar: 100000.
    atm: 101325.
    deg: 0.0174533
    arcmin: 0.000290888
    arcsec: 4.84814e-06
dv> unithelp()

unithelp() describes all unit conversion factors in structure un
S.Marshall 11-30-2010

    Most of these values are from
     http://www.nist.gov/pml/wmd/metric/upload/SP1038.pdf
     via http://www.nist.gov/pml/wmd/metric/metric-pubs.cfm
    Additional sources: http://ssd.jpl.nasa.gov/?constants
     and http://www.iau.org/public/measuring/

    Note that definitions vary for mile, pound, ounce, gallon,
     calorie, and horsepower. Those used here are the most common.

    The values here are the ratio of the non-SI unit to the
     corresponding SI unit. For instance,
     un.ft = 0.3048 = (one foot)/(one meter), so
     (one foot) = (value of un.ft)*(one meter) = 0.3048 m

    in   =     0.0254 m             Inch
    ft   =     0.3048 m             Foot (12 inches)
    mi   =  1609.344 m              Mile (5280 feet)
    AU   =  1.49597870691e+11 m     Astronomical unit
    ly   =  9.4607304725808e+15 m   Light-year (c*Jyr)
    pc   =  3.0856775813e+16 m      Parsec

    oz   =  0.028349523125 kg       Ounce mass (avoirdupois, 1/16 lb)
    lb   =  0.45359237 kg           Pound mass (avoirdupois)

    day  =  86400 s                 Day (24 hours)
    Jyr  =  3.15576e+07 s           Julian year (365.25 days)

    floz =  2.95735295625e-05 m^3   Fluid ounce (1/128 gal)
    L    =  0.001 m^3               Liter
    gal  =  0.003785411784 m^3      US gallon (231 cubic inches)

    mph  =  0.44704 m/s             Mile per hour

    ozf  =  0.278013850953781 N     Ounce force
    lbf  =  4.4482216152605 N       Pound force

    cal  =  4.184 J                 Calorie (thermochemical)
    tTNT =  4.184e+09 J             TNT equivalent tonne

    hp   =  746 W                   Horsepower (electric)

    mbar =     100 Pa               Millibar
    torr =     133.322368421053 Pa  Torr (1/760 atm)
    psi  =    6894.75729316836 Pa   Pound per square inch
    bar  =  100000 Pa               Bar
    atm  =  101325 Pa               Standard atmosphere

    deg    =  0.0174532925199433 rad     Degree (pi/180 radians)
    arcmin =  2.908882086657216e-04 rad  Arcminute (1/60 degree)
    arcsec =  4.848136811095360e-06 rad  Arcsecond (1/60 arcminute)

    All except AU and pc are exact (to double precision)