I need to display very small numbers using scientific notation to only three decimal places:

     e.g., display 0.00000000000325394873638... as '3.254e-12'.

FloatToStr will return a string in scientific notation when the number is very small.  However, the coefficient will have 17 or so decimal places before getting to the exponential portion: e.g., 'e-12'.  This fills up the output edit component, making it look like the result is 3.25394873638... .  I can scroll over to the e-12, but to the user it looks as though the answer is 3.2539....

Limiting the number of decimals places to 3 does not work when FloatToStr decides to use scientific notation.  I get instead 0.000 rather than 3.254e-12.

One solution is to have a ridiculously wide edit box, which does not look good.

Questions:
1. Is there a way to force the FloatToStr output string to be in scientific notation?
2. If the answer is yes, is there any way to limit the number of decimal places?

PKH,

<< Limiting the number of decimals places to 3 does not work when FloatToStr decides to use scientific notation.  I get instead 0.000 rather than 3.254e-12. >>

This is because FloatToStr with specified decimal places causes rounding, and that value is rounded to 0.000.

<< 1. Is there a way to force the FloatToStr output string to be in scientific notation? >>

No, not at this time.  I can certainly add a new function for this.  I'll also need to add a dataset column property for specifying whether one wants data displayed in scientific format (or not).

As a workaround, if you do something like this:

  ExponentialEdit.Text:=FloatToStr(StrToFloat(ExponentialEdit.Text));

with a value of '0.00000000000325394873638', it *will* serve to convert the number into scientific format.  However, you can't explicitly limit the number of decimal places.

Tim Young
Elevate Software
www.elevatesoft.com