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how should a program ask for no SI prefix?
11-24-2015, 03:14 PM
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how should a program ask for no SI prefix?
With SI written units, the absence of an SI prefix is indicated by a null: as in "m" instead of "mm".

I may have missed it (I have only looked at free specs) but I have not seen an equivalent that would suit a program.

If I have a pop-up selector (CHOOSE or INPUT) prompting for K,M,G,... how should I signify " no prefix"? Which will probably be the default.
The problem with "no prefix" is:
- its longer than K, so might not fit your form
- it needs translation
- The opposite of "no prefix" is "a prefix", not a specific one.

Using a null entry (equivalent to the written " m" for metres) is inconvenient, particularly on the HP Prime: There is no clue that this is your prefix input rather than something else, and HP Prime's default prompt is for a value - the inexperienced user is likely to try to type in a number rather than select a choice.

For mathematical users one might avoid translation by using a number but even this can be confusing. Should one specify " 1" as in multiply by 1,1000,1000000? Or should one specify ^0 as in 1e6,1e3,1e0? Of course either could be used - but are there any hints as to what works and what doesn't? Does the SI organisation have any recommendations? (And if not, why not?)

Stephen Lewkowicz (G1CMZ)
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how should a program ask for no SI prefix? - StephenG1CMZ - 11-24-2015 03:14 PM



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