Difference between revisions of "LlLog"

From Second Life Wiki
Jump to: navigation, search
m
m (<lsl> tag to <source>)
 
(One intermediate revision by one other user not shown)
Line 1: Line 1:
{{LSL_Function
+
{{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
Line 5: Line 5:
 
|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.
+
|return_text=that is the {{Wikipedia|natural logarithm|w=n}} of '''val'''.<br/>If '''val''' <= 0 return 0.0 instead.
 
|spec
 
|spec
 
|caveats
 
|caveats
 
|constants
 
|constants
 
|examples=
 
|examples=
<lsl>
+
<source lang="lsl2">
 
default
 
default
 
{
 
{
Line 20: Line 20:
 
   }
 
   }
 
}
 
}
</lsl>
+
</source>
<lsl>
+
<source lang="lsl2">
 
float findexp(float result, float base)
 
float findexp(float result, float base)
 
{
 
{
Line 35: Line 35:
 
}
 
}
  
</lsl>
+
</source>
 
|helpers
 
|helpers
 
|also_functions={{LSL DefineRow||[[llLog10]]|}}
 
|also_functions={{LSL DefineRow||[[llLog10]]|}}
Line 42: Line 42:
 
|also_events
 
|also_events
 
|also_tests
 
|also_tests
|also_articles={{LSL DefineRow||{{Wikipedia|Natural_logarithm}}|}}
+
|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>
+
<source lang="lsl2">float LogBaseN = llLog(value) / llLog(Base); //This technique introduces errors but is the only way</source>
  
 
If Base is a constant, your script will run faster if you calculate it's log and divide by that constant instead.
 
If Base is a constant, your script will run faster if you calculate it's log and divide by that constant instead.

Latest revision as of 11:19, 22 January 2015

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

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

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.

float LogBaseN = llLog(value) / llLog(Base); //This technique introduces errors but is the only way

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 );