Home

The library

Generating the library

C++

Download

The names of the types follow the following convention. They are composed by four parts, one for each dimension. Each part, in turn, is composed of two subparts, a distinctive letter and a representation of the exponent for this dimension, as follows.

• m exponent for length
• k exponent for mass
• s exponent for time
• a exponent for electric charge

where exponents are prefixed by '_' instead of '-' if they are negative. For example, type m_2k0s1a0 represents dimension L^-2T.

Some types have more conventional names. The current such list is shown in the sidebar. Note that only those types that are inside the bounds set when the library was generated will be found in it. The standard download offers types that exist between the following bounds:

• length between -2 and 2, inclusive
• mass between -1 and 1, inclusive
• time between -2 and 1, inclusive
• electric charge between -1 and 1, inclusive

There is a slight bias in favor of mechanics, which means that some interesting types in electromagnetics are not inside the library. This was inevitable, in order to keep the size of the library under control If one wishes a different set of types, one can generate it with a different set of bounds, and even include other dimensions I left out, like temperature.

Operations that are implemented are:

• multiplication by numbers (doubles)
• addition and subtraction of same types
• multiplication and division where the other type and the resulting type both exist in the library

The types have an operation to return a string that represents the correspoding units of measurement. Where available, specific units are used. For example, instead of m·kg·s^-2, one will see N (Newton). The current such list is shown in the sidebar.

Types implement interface DimensionedValue. Its precise definition of it is bound to change, but currently it offers the following operations:

• retrieve value as double
• retrieve exponent of any dimension
• retrieve units as a string
• find out if the units is a derived unit (see sidebar)

The library for C# corresponds to an assembly containing all the types. The types themselves are structs that define operator overloads for arithmetic operations and conversions to double. All types are in namespace Dimenso.

The library for Java corresponds to a JAR containing all the types. The types themselves are classes that define operations as methods, with the same names as the corresponding operations of BigDecimal. All types are in package org.dimenso.

expected	actual
m1k0s0a0	length
m2k0s0a0	area
m3k0s0a0	volume
m1k0s_1a0	velocity
m1k0s_2a0	acceleration
m0k1s0a0	mass
m0k0s0a0	time
m1k1s_1a0	momentum
m2k1s_1a0	angular _momentum
m0k0s_1a0	frequency
m1k1s_2a0	force
m_1k1s_2a0	pressure
m_1k1s_1a0	viscosity
m2k1s_2a0	energy
m2k1s_3a0	power
m0k0s1a1	charge
m2k1s_3a_1	potential
m_2k_1s4a2	capacitance
m2k1s_3a_2	resistance
m_2k_1s3a2	conductance
m2k1s_2a_1	magnetic_flux
m0k1s_2a_1	magnetic_flux _density
m2k1s_2a_2	inductance

Not all types exist in the standard download, because the bounds it was built with exclude some of them.

expected	derived
s-1	Hz
m·kg·s-2	N
m-1·kg·s-2	Pa
m-1·kg·s-1	Pa·s (Poiseuille)
m2·kg·s-2	J
m2·kg·s-3	W
s·A	C
m2·kg·s-3·A-1	V
m-2·kg-1·s4·A2	F
m2·kg·s-3·A-2	Ohm
m-2·kg-1·s3·A2	S
m2·kg·s-2·A-1	Wb
kg·s-2·A-1	T
m2·kg·s-2·A-2	H

Not all cases exist in the standard download, because the bounds it was built with exclude some of the types.