Difference between revisions of "LlLog"

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{{LSL_Function
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{{LSL Function
 
|func=llLog
 
|func=llLog
 
|func_id=265|func_sleep=0.0|func_energy=10.0
 
|func_id=265|func_sleep=0.0|func_energy=10.0
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|func_footnote=To get the base 10 logarithm use {{LSLG|llLog10}}.
 
|func_footnote=To get the base 10 logarithm use {{LSLG|llLog10}}.
 
|func_desc
 
|func_desc
|return_text=that is the {{Wikipedia|Natural_logarithm|natural logarithm}} of '''val'''.<br/>If '''val''' <= 0 return 0.0 instead.
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|return_text=that is the {{Wikipedia|natural logarithm|w=n}} of '''val'''.<br/>If '''val''' <= 0 return 0.0 instead.
 
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|caveats
 
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|also_events
 
|also_events
 
|also_tests
 
|also_tests
|also_articles={{LSL DefineRow||{{Wikipedia|Natural_logarithm}}|}}
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|also_articles={{LSL DefineRow||{{Wikipedia|Natural logarithm}}|}}
 
|notes=There are only two log functions [[llLog]] and [[llLog10]]. Errors introduced as a result of floating-point arithmetic are most noticable when working with logarithms. [[llLog]] should be used instead of [[llLog10]] when converting the base of the logarithm.
 
|notes=There are only two log functions [[llLog]] and [[llLog10]]. Errors introduced as a result of floating-point arithmetic are most noticable when working with logarithms. [[llLog]] should be used instead of [[llLog10]] when converting the base of the logarithm.
 
<lsl>float LogBaseN = llLog(value) / llLog(Base); //This technique introduces errors but is the only way</lsl>
 
<lsl>float LogBaseN = llLog(value) / llLog(Base); //This technique introduces errors but is the only way</lsl>

Revision as of 12:40, 17 February 2012

Summary

Function: float llLog( float val );

Returns a float that is the natural logarithm of val.
If val <= 0 return 0.0 instead.

• float val

To get the base 10 logarithm use llLog10.

Examples

<lsl> default {

 state_entry()
 {
   float num1 = llFrand(100.0);
   llOwnerSay("The natural logarithm of " + (string)num1 + " is " + (string)llLog(num1));
 }

} </lsl> <lsl> float findexp(float result, float base) {

   return llLog(result)/llLog(base);

} default {

   touch_start(integer total_number)
   {
       llSay(0, (string)findexp(8.0,2.0));
       //returns 3.0
   }

}

</lsl>

Notes

There are only two log functions llLog and llLog10. Errors introduced as a result of floating-point arithmetic are most noticable when working with logarithms. llLog should be used instead of llLog10 when converting the base of the logarithm. <lsl>float LogBaseN = llLog(value) / llLog(Base); //This technique introduces errors but is the only way</lsl>

If Base is a constant, your script will run faster if you calculate it's log and divide by that constant instead.


Useful natural logarithms
Number logarithm
2 0.69314718056
4 1.38629436112
8 2.07944154168
10 2.30258509299
16 2.77258872224
32 3.4657359028
64 4.15888308336
128 4.85203026392
256 5.54517744448

See Also

Functions

•  llLog10
•  llPow
•  llSqrt

Articles

•  Wikipedia:Natural logarithm

Deep Notes

Search JIRA for related Issues

Signature

function float llLog( float val );