Difference between revisions of "LlLog"

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m (<lsl> tag to <source>)
 
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{{LSL_Function
{{LSL Function
|func=llLog
|func_id=265|func_sleep=0.0|func_energy=10.0
|func_id=265|func_sleep=0.0|func_energy=10.0
|func=llLog|return_type=float|p1_type=float|p1_name=val
|return_type=float|p1_type=float|p1_name=val
|func_footnote
|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=
<source lang="lsl2">
default
{
  state_entry()
  {
    float num1 = llFrand(100.0);
 
    llOwnerSay("The natural logarithm of " + (string)num1 + " is " + (string)llLog(num1));
  }
}
</source>
<source lang="lsl2">
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
    }
}
 
</source>
|helpers
|helpers
|also_functions
|also_functions={{LSL DefineRow||[[llLog10]]|}}
{{LSL DefineRow||[[llPow]]|}}
{{LSL DefineRow||[[llSqrt]]|}}
|also_events
|also_events
|also_tests
|also_tests
|also_articles=*{{Wikipedia|Natural_logarithm}}
|also_articles={{LSL DefineRow||{{Wikipedia|Natural logarithm}}|}}
|notes
|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.
<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.
 
 
{{{!}} class="sortable" {{Prettytable}}
{{!}}+Useful natural logarithms
{{!}}-{{Hl2}}
! Number
! logarithm
{{!}}-
{{!!}} 2 {{!!}} {{#ln:2}}
{{!}}-
{{!!}} 4 {{!!}} {{#ln:4}}
{{!}}-
{{!!}} 8 {{!!}} {{#ln:8}}
{{!}}-
{{!!}} 10 {{!!}} {{#ln:10}}
{{!}}-
{{!!}} 16 {{!!}} {{#ln:16}}
{{!}}-
{{!!}} 32 {{!!}} {{#ln:32}}
{{!}}-
{{!!}} 64 {{!!}} {{#ln:64}}
{{!}}-
{{!!}} 128 {{!!}} {{#ln:128}}
{{!}}-
{{!!}} 256 {{!!}} {{#ln:256}}
{{!}}}
 
 
|permission
|permission
|negative_index
|negative_index
|sort=Log
|cat1=Math
|cat1=Math
|cat2
|cat2

Latest revision as of 12:19, 22 January 2015

Summary

Function: float llLog( float val );

Returns a float that is the "Wikipedia logo"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 {{#ln:2}}
4 {{#ln:4}}
8 {{#ln:8}}
10 {{#ln:10}}
16 {{#ln:16}}
32 {{#ln:32}}
64 {{#ln:64}}
128 {{#ln:128}}
256 {{#ln:256}}

See Also

Functions

•  llLog10
•  llPow
•  llSqrt

Articles

•  "Wikipedia logo"Natural logarithm

Deep Notes

Search JIRA for related Issues

Signature

function float llLog( float val );