DIMENSION - tagging values with units

Class for tagging values with units. Provides for transparent conversion, unit checking & combining.

Joe engineer's script works in radians and meters. The lab data files are in degrees and inches and the drawings are in mm. Joe tags everything with dimensions and never worries again about conversions. He even discovers a bug where a value he thought represented area really represents distance.

Whirlwind Tour:
>> side = dimension(500,'m')
side = 500 m
>> height = dimension(2.1,'km');
>> height + side
ans = 2.6 km
>> side + height
ans = 2600 m
>> height > dimension(1,'mi')
ans = 1
>> convert(side*height,'acre')
ans = 259.461 acre
>> msquared = dimension(1,'m',2)
msquared = 1 m^2
>> convert(side*height,msquared)
ans = 1050000 m^2
>> speed = dimension(60,'mi','hr',-1);
>> value(speed)
ans = 60
Or
>> speed.value
ans = 60
>> convert(speed,'kph')
ans = 96.5606 kph
>> ubase(speed)
ans = 26.8224 m s^-1
>> ubase(dimension(1,'btu'))
ans = 1055.06 kg m^2 s^-2
>> convert(height,'kg')
??? Error ==> units are incompatable
>> height + speed
??? Error ==> units are incompatable
>> speed * dimension(1.5,'hr')
ans = 90 mi
>> thickness = dimension([1,2;3,4],'in');
thickness = 1 2
3 4 in
>> thickness(2,1)
ans = 3 in
>> [ thickness [ side/1000; height/1000 ] ]
ans = 1 2 19.685
3 4 82.677 in
>> thickness'
ans = 1 3
2 4 in
>> angle = dimension(30,'deg');
>> tan(angle)
ans = 0.57735
Any value can be used as an argument to DIMENSION:
>> i_time = dimension(1*i,'s');
Users can define their own units based on previously defined units or redefine existing units:
>> frlng = dimension(220,'yd');
>> add_unit(frlng,'furlong');
>> convert(height,'furlong')
ans = 10.439 furlong
>> add_base(dimension, 'beaut');
>> add_unit(dimension(.75,'beaut','joule',-1),'tnt');
>> ubase(dimension(700,'tnt'))
ans = 525 beaut s^2 kg^-1 m^-2

Some defined units:
s, sec, min, hr, dy, wk, yr, mon, millenium
m, cm, mm, a, km, ft, in, mil, yd, mi, nm, ly, au, parsec
r, radian, deg, arcmin, arcsec, grad, cycle, rev
kg, gm, mg, tonne, lbm, oz, slug, ton, amu
k, kelvin, rankine
amp, ma
mole, mol
bit, byte, kB, MB, GB, TB
cd, candle
dollar, $, cent
cc, l, ml, gal, qt, floz
kph, knot, mph, c
Hz, KHz, MHz, GHz, rpm
nt, dyne, lb, lbf
joule, erg, cal, btu, ev, mev, kwh
sr, coulomb, ftlb, watt, gray, farad, ohm, mho, v, henry, tesla, gauss, wb

This is beta software and still in the bug-killing stage. Everything shown above works correctly, though.