# Difference between revisions of "LlLog"

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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 | + | |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 | default | ||

{ | { | ||

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} | } | ||

} | } | ||

− | </ | + | </source> |

− | < | + | <source lang="lsl2"> |

float findexp(float result, float base) | float findexp(float result, float base) | ||

{ | { | ||

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− | </ | + | </source> |

|helpers | |helpers | ||

|also_functions={{LSL DefineRow||[[llLog10]]|}} | |also_functions={{LSL DefineRow||[[llLog10]]|}} | ||

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|also_events | |also_events | ||

|also_tests | |also_tests | ||

− | |also_articles={{LSL DefineRow||{{Wikipedia| | + | |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. | ||

− | < | + | <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

LSL Portal | Functions | Events | Types | Operators | Constants | Flow Control | Script Library | Categorized Library | Tutorials |

## Summary

Function: float**llLog**( float val );

265 | Function ID |

0.0 | Forced Delay |

10.0 | Energy |

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.

## Caveats

## 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.

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 |