manual:chapter3:units

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revision Previous revision
Next revision
Previous revision
manual:chapter3:units [2019/09/18 16:30]
jojo1973 [Multiples and Submultiples]
manual:chapter3:units [2019/11/19 13:34] (current)
claudio [Custom Units]
Line 27: Line 27:
 Multiples and submultiples of many units are obtained by prefixing them with the standard SI prefixes. Therefore, ''1_dal'' is equivalent to ''10_l'' and ''3.5_MHz'' is equivalent to ''3500000_Hz''. Multiples and submultiples of many units are obtained by prefixing them with the standard SI prefixes. Therefore, ''1_dal'' is equivalent to ''10_l'' and ''3.5_MHz'' is equivalent to ''3500000_Hz''.
  
-There is only one exception: prefixes can'be used if the resulting name matches an already existing unitFor example, it'not possible use ''_[min]'' to mean milliinches because ''_[min]'' is already defined and corresponds to the time unit "minute".+SI prefixes can be used with all SI units and many non-SI units where SI prefixes are common usageOther non-SI units do not accept prefixes
  
 ^  SI Prefix  ^  Factor  ^  Name  ^    ^  SI Prefix  ^  Factor  ^  Name  ^   
Line 67: Line 67:
 Units in newRPL can be arbitrary symbols, not just the ones predefined in the system. For example, adding ''3_apples'' and ''2_apples'' will produce ''5_apples'' as expected. In this case, ''apples'' is a custom unit without a definition. Units without a definition are considered base units. The system already includes base units for mass, length, time, etc. but any number of new base units can be added simply by using new symbols. Units in newRPL can be arbitrary symbols, not just the ones predefined in the system. For example, adding ''3_apples'' and ''2_apples'' will produce ''5_apples'' as expected. In this case, ''apples'' is a custom unit without a definition. Units without a definition are considered base units. The system already includes base units for mass, length, time, etc. but any number of new base units can be added simply by using new symbols.
  
-Custom units can also be defined as derived units, in terms of other base units. This is done with the ''UDEFINE'' command. For example typing ''750_ml'' ''%%'bigmug'%%'' ''UDEFINE'' would define a unit named ''bigmug'' as 750 ml. From that moment ''bigmug'' can be used in the exact same way as any system-defined unit, and it will be considered consistent with all other volume units.+Custom units can also be defined as derived units, in terms of other base units. This is done with the ''UDEFINE'' command. For example typing ''750_ml'' ''%%'mug'%%'' ''UDEFINE'' would define a unit named ''mug'' as 750 ml. From that moment ''mug'' can be used in the exact same way as any system-defined unit, and it will be considered consistent with all other volume units.
  
-New units can also be defined in terms of new (unknown) base units. For example typing ''3_apples'' ''%%'oranges'%%'' ''UDEFINE'' will define ''oranges'' as equivalent to 3 ''apples'', where ''apples'' is a base unit (amount of fruit?).+Custom units may also accept SI prefixes, but this needs to be explicitly enabled during the unit definition. To create a custom unit that accepts SI prefixes, the name of the unit needs to be preceded by a question mark ''?'' when the unit is defined. For example, following the previous example, for the unit ''mug'' to accept SI prefixes, the definition should be done typing ''750_ml'' ''%%'?mug'%%'' ''UDEFINE'' creates a unit ''mug'' exactly as before, except now ''1_[Mmug]'' ''UBASE'' will produce ''750_m^3'', as expected. 
 + 
 +New units can also be defined in terms of new (unknown) base units. For example typing ''3_apples'' ''%%'oranges'%%'' ''UDEFINE'' will define ''oranges'' as equivalent to 3 ''apples'', where ''apples'' is a base unit (amount of fruit?that may or may not have been explicitly defined before.
 From that moment the addition ''2_[oranges]+3_[apples]'' will result in ''3_oranges'' since the units of the result will match the units of the left operand, and the 3 apples were automatically converted to 1 orange. From that moment the addition ''2_[oranges]+3_[apples]'' will result in ''3_oranges'' since the units of the result will match the units of the left operand, and the 3 apples were automatically converted to 1 orange.
  
Line 77: Line 79:
 ==== Available Units ==== ==== Available Units ====
  
-This is a list of the units available in the ''Units'' menu on newRPL:+This is a list of the units available in the ''Units'' menu on newRPL. All the conversion factors are meant to be exact, not approximated. 
 + 
 +=== Length ===
  
-| **Length** |||| +Unit Unit name Definition Description ^ Prefixable ^ 
-Unit Unit name Definition Description | +| 1_m | metre | 1_m  | Base SI unit of length | {{fa>check?lg&color=green}} 
-| 1_m | metre | 1_m  | Base SI unit of length |  +| 1_cm | centimetre | 1_cm = 0.01_m | SI, metric | {{fa>times?lg&color=red}} 
-| 1_cm | centimetre | 1_cm = 0.01_m | SI length |  +| 1_mm | millimetre | 1_mm = 0.001_m | SI, metric | {{fa>times?lg&color=red}} 
-| 1_mm | millimetre | 1_mm = 0.001_m | SI length |  +| 1_yd | yard | 1_yd = 3_ft | US Customary | {{fa>times?lg&color=red}} 
-| 1_yd | yard | 1_yd = 3_ft | US customary length |  +| 1_ft | foot | 1_ft = 12_in | US Customary | {{fa>times?lg&color=red}} |  
-| 1_ft | foot | 1_ft = 12_in | US customary length |  +| 1_in | inch | 1_in = 0.0254_m | US Customary | {{fa>times?lg&color=red}} 
-| 1_in | inch | 1_in = 0.0254_m | US customary length |  +| 1_Mpc | megaparsec | 1_Mpc = 1000000_pc | Astronomical length | {{fa>times?lg&color=red}} 
-| 1_Mpc | megaparsec | 1_Mpc = 1000000_pc | Astronomical length |  +| 1_pc | parsec | 1_pc = (648000/π)_au | Astronomical length | {{fa>times?lg&color=red}} 
-| 1_pc | parsec | 1_pc = (648000/π)_au | Astronomical length |  +| 1_lyr | light year | 1_lyr = 9460730472580800_m | Astronomical length | {{fa>times?lg&color=red}} 
-| 1_lyr | light year | 1_lyr = 365.25_d*c | Astronomical length |  +| 1_au | astronomical unit | 1_au = 149597870700_m | SI astronomical length | {{fa>times?lg&color=red}} 
-| 1_au | astronomical unit | 1_au = 149597870700_m | SI astronomical length |  +| 1_km | kilometre | 1_km = 1000_m | SI, metric | {{fa>times?lg&color=red}} 
-| 1_km | kilometre | 1_km = 1000_m | SI length |  +| 1_mi | mile | 1_mi = 5280_ft | US Customary | {{fa>times?lg&color=red}} 
-| 1_mi | mile | 1_mi = 5280_ft | US customary length |  +| 1_nmi | nautical mile | 1_nmi = 1852_m | non-SI length | {{fa>times?lg&color=red}} 
-| 1_nmi | nautical mile | 1_nmi = 1852_m | non-SI length |  +| 1_miUS | surveying mile | 1_miUS = 5280_ftUS | US surveying length | {{fa>times?lg&color=red}} 
-| 1_miUS | surveying mile | 1_miUS = 5280_ftUS | US surveying length | +| 1_chain | surveying chain | 1_chain = 66_ftUS | US surveying length | {{fa>times?lg&color=red}} 
-| 1_chain | surveying chain | 1_chain = 66_ftUS | US surveying length |  +| 1_rd | rod | 1_rd =16.5_ft | US customary length | {{fa>times?lg&color=red}} 
-| 1_rd | rod | 1_rd =16.5_ft | US customary length |  +| 1_rdUS | surveying rod | 1_rdUS =16.5_ftUS | US surveying length | {{fa>times?lg&color=red}} 
-| 1_rdUS | surveying rod | 1_rdUS =16.5_ftUS | US surveying length |  +| 1_fath | surveying fathom | 1_fath =6_ftUS | US surveying length | {{fa>times?lg&color=red}} 
-| 1_fath | surveying fathom | 1_fath =6_ftUS | US surveying length |  +| 1_ftUS | surveying foot | 1_ftUS = 1200/3937_m | US surveying length | {{fa>times?lg&color=red}} 
-| 1_ftUS | surveying foot | 1_ftUS = 1200/3937_m | US surveying length |  +| 1_mil | thousandth of inch | 1_mil = 0.001_in | US customary length | {{fa>times?lg&color=red}} 
-| 1_mil | thousandth of inch | 1_mil = 0.001_in | US customary length |  +| 1_µ | micron | 1_µ = 1_µm | SI length | {{fa>times?lg&color=red}} 
-| 1_µ | micron | 1_µ = 1_µm | SI length |  +| 1_Å | ångström | 1_Å = 0.1_nm | non-SI length | {{fa>times?lg&color=red}} 
-| 1_Å | ångström | 1_Å = 0.1_nm | non-SI length |  +| 1_fermi | fermi  | 1_fermi = 1_fm | SI length | {{fa>times?lg&color=red}} |
-| 1_fermi | fermi  | 1_fermi = 1_fm | SI length | +
  
 | **Area** |||| | **Area** ||||
  • manual/chapter3/units.1568849428.txt.gz
  • Last modified: 2019/09/18 16:30
  • by jojo1973