I would like an option for displaying results in engineering notation/format
ie where the exponents are all multiples of 3. This is a lamented feature of the old HP calculator.
eg scientific format = 3.7*10^4 ; engineering format = 37*10^3

You can do that right now.

The attached help page is found in the interactive handbook under

Toolbar [?]> Units of Measurement> Units in Results Display

Can you specify such an algorithm? When would you change? 1.005 km or 1005 m? Would you also use the prefixes hecto deca deci and centi? No? But i.e. centimetre is widely used in construction engineering and hectolitres in the brewing industry. In mechanical engineering we use millimetres even for long measurements up to 50000 mm and short measurements down to one thousandth millimetre.

Would you rather write 1 day instead of 86400 s? Keep in mind day is not a SI unit just as degrees, litres and tonnes. So which prefix should Smath automatically use?

Because I do not see the algorithm I prefer setting my units manually. The only thing I could imagine is a set of tables for specific industries and units. I.e. use tonne for weights above 1000 kg (instead of Megagramms), in mechanical industry always use millimeters for lengths, use hours for time >1000 s and so on.

Edited by user 15 November 2014 13:41:12(UTC)  | Reason: Not specified

Yes, here are two examples, if Andrei would like a template:

In Javascript
http://www.i2cchip.com/miscstuff/functionLib.js
(function is Real2Eng)

In Pascal:
http://www.i2cchip.com/miscstuff/engfmt.zip
It is inside spstring.pas. The helpfile explains in detail what the function Float2EngStr does:

function Float2EngStr(R:extended;MantissaDigits:word;FormatStr:string; Suffix:string):string

turns a real no. into a Engineering formatted string of PRECISION digits accuracy,
Engineering Format shifts exponent to powers of 3 (familiar to HP calculator users)
Will also suffix appropriate letter multipliers instead of E+XX eg k,M etc

To use defaults try Float2EngStr(1.0123456E4,0,'','' ) -> ' 10.12E+03'

MantissaDigits: number of digits (not including decimal) min is 3; 4 recomended

(default=4)

FormatStr: This set of chars sets how sign and exponents appear.
(default=' E-2' )
Format Str[1] sets how the leading char or sign appears
' ' leading <space> for +ve , - for -ve
'|' no leading char for +ve, - for -ve
'+' always has leading + or -;
'-' no leading char for +ve,reduces precision by 1 for -ve to accomodate -
only if precision>=4; recommended for >=5. Keeps length constant for +ve & -ve #'s
FormatStr[2] sets exponent style and case. if lower case will use lower case 'e'
'E','e' : force exponential form
'F','f' : use prefix chars where possible (ie for E-15 to E+14 )
FormatStr[3] sets how exponent sign appears
'+' : always have + or - (string will be constant length)
'|' : no + for +ve, - for -ve (string will change length)
'-' : use + for +ve unless exponent>digits, then drop + to keep length constant
' ' : <space> is NOT A VALID OPTION. Pascal read routines require EXXX not E XXX
FormatStr[4] number of digits in ExponentDigits (range '1' to '4' )
If exponent has more digits than ExponentDigits (very large or very close to zero)
then length will be greater. See ClipFloat()

If either FormatStr or MantissaDigits are invalid, sets to default.
eg
Float2EngStr(1.978269E+07,5,' F-2','Hz' ) = '19.783 MHz'
Float2EngStr(1.978269E+07,5,' E-2','' ) = '19.783E+06'
Float2EngStr(1.978269E-02,5,'-f-2','' ) = '-19.78e-03'
Float2EngStr(1.978269E+103,5,'-f-2','' ) = '19.783e102'
Float2EngStr(-1.978269E+103,5,'-F-2','' ) = '-19.78E102'

Edited by user 06 December 2014 10:50:52(UTC)  | Reason: Not specified