Difference between revisions of "Category:LSL Float"

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(Useful Snippets: added a less efficient method)
(Useful Snippets: Gave Strife's function precedence since it's the more robust, clarified the caveats of mine (having investigated them a bit more fully).)
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== Useful Snippets ==
 
== Useful Snippets ==
 
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The following is a useful way to validate a string that may be a float; it isn't 100% accurate (to do so is considerably more complex), however it will match all but the most extreme float values; so as long as you are using what are typical values in LSL (don't really go beyond 4 or 5 decimal places, or beyond the billions in values) then it is by far the most efficient method.
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If you need to validate an arbitrary float without limitations then the following function is ideal:
<lsl>integer isValidFloat(string s) { return (float)(s + "1") != 0.0; }</lsl>
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If you need to validate an arbitrary float without the above limitations the following is more robust. However it is less efficient.
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<lsl>integer isValidFloat(string s) { return (string)((float)s) != (string)((float)("-" + llStringTrim(s, STRING_TRIM_HEAD))); }</lsl>
 
<lsl>integer isValidFloat(string s) { return (string)((float)s) != (string)((float)("-" + llStringTrim(s, STRING_TRIM_HEAD))); }</lsl>
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However, the following is more efficient, but comes with the noted caveats. If these are not an issue to you then it is the recommended option, particularly under Mono:
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<lsl>integer isValidFloat(string s) { return (float)(s + "1") != 0.0; }</lsl>
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'''Caveats''':
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* Under LSO-LSL scientific notation with an exponent greater than 3 will fail (throw a Math Error). Mono is unaffected as it supports <code>infinity</code>.
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* Under both Mono and LSO-LSL you may find strange results if dealing with strings containing more than 9 decimal places. Remember that string casting in LSL only gives up to 6 so is safe, and human input is rarely going to be that accurate, plus values that small are not usually all that useful.
 
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Revision as of 15:15, 22 October 2010

Floating point data types are 32 bit numbers in IEEE-754 form. If you want a decimal point in your number, then it is a float.

The Range is 1.175494351E-38 to 3.402823466E+38

They can be specified in scientific notation like 2.6E-5.

If a function requires a float as a parameter, and the number is an integer (e.g. 5), be sure to add a .0 so it is created as a float (e.g. 5.0)

If you are dividing 2 constants, be sure to define them as floats or your result may get rounded. Better yet, do the math on your calculator and save the server some cycles.

Examples

<lsl>float min = 1.175494351E-38; float max = 3.402823466E+38; float sci = 2.6E-5; float sci_a = 2.6E+3; float sci_b = 2.6E3; float sci_c = 26000.E-1; float f = 2600;//implicitly typecast to a float float E = 85.34859; </lsl>

Useful Snippets

If you need to validate an arbitrary float without limitations then the following function is ideal: <lsl>integer isValidFloat(string s) { return (string)((float)s) != (string)((float)("-" + llStringTrim(s, STRING_TRIM_HEAD))); }</lsl>

However, the following is more efficient, but comes with the noted caveats. If these are not an issue to you then it is the recommended option, particularly under Mono: <lsl>integer isValidFloat(string s) { return (float)(s + "1") != 0.0; }</lsl> Caveats:

  • Under LSO-LSL scientific notation with an exponent greater than 3 will fail (throw a Math Error). Mono is unaffected as it supports infinity.
  • Under both Mono and LSO-LSL you may find strange results if dealing with strings containing more than 9 decimal places. Remember that string casting in LSL only gives up to 6 so is safe, and human input is rarely going to be that accurate, plus values that small are not usually all that useful.

See Also

Articles

Subcategories

This category has only the following subcategory.

Pages in category "LSL Float"

The following 8 pages are in this category, out of 8 total.