Difference between revisions of "LlLog"

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|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>
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 +
If Base is a constant, your script will run faster if you calculate it's log and divide by that constant instead.
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 +
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{{{!}} class="sortable" {{Prettytable}}
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{{!}}+Useful natural logarithms
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{{!}}-{{Hl2}}
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! Number
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! logarithm
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{{!}}-
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{{!!}} 2 {{!!}} {{#ln:2}}
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{{!}}-
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{{!!}} 4 {{!!}} {{#ln:4}}
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{{!}}-
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{{!!}} 8 {{!!}} {{#ln:8}}
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{{!}}-
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{{!!}} 10 {{!!}} {{#ln:10}}
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{{!}}-
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{{!!}} 16 {{!!}} {{#ln:16}}
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{{!}}-
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{{!!}} 32 {{!!}} {{#ln:32}}
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{{!}}-
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{{!!}} 64 {{!!}} {{#ln:64}}
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{{!}}-
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{{!!}} 128 {{!!}} {{#ln:128}}
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{{!}}-
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{{!!}} 256 {{!!}} {{#ln:256}}
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{{!}}}
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 +
 
|permission
 
|permission
 
|negative_index
 
|negative_index

Revision as of 07:53, 16 June 2011

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 );