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===== Function: llLog =====

<code lsl2>
float llLog(float arg)
</code>

Returns the natural logarithm of the argument. The natural logarithm is a logarithm in base $econst (the Euler constant, which is approximately 2.7182818).

===== Parameters =====

=== arg ===
The float value whose natural logarithm is to be calculated.

===== Return value =====

Returns a $lty[float] which is the natural logarithm of the argument.

===== Notes =====

  * In order to make sense, the argument must be greater than 0.0; a value of 0.0 or less yields 0.0.
  * The function returns $pinf if the input is $pinf, and 0.0 if the input is $minf or $nan.
  * To calculate the logarithm in base 10, $lfn[llLog10] can be used.
    * To calculate the logarithm in any other base, divide the result of this function by the logarithm of that base.
    * For example, to calculate the logarithm in base 2 of a number, use ''llLog(number)/llLog(2)''. Since the latter is constant, to save calculations and memory you can instead pre-calculate the reciprocal and multiply by it, like this: ''llLog(number)*1.44269504'' will give you the logarithm in base 2, because ''1/llLog(2)'' equals approx. 1.44269504.
  * There is no built-in inverse of this function. To raise the Euler constant to a power, use $lfn[llPow]. But there is also no built-in definition for the Euler constant either, so you will need to use its value, which is approx. 2.7182818.

===== Short examples =====

<code lsl2>
float f;
f = llLog(2.7182818); // sets f to 1 approx.
f = llLog(1);   // sets f to 0
f = llLog(2);   // sets f to 0.693147 approx.
f = llLog(0.5); // sets f to -0.693147 approx.
f = llLog(-1);  // sets f to 0
f = llLog(8)*1.44269504; // sets f to 3 approx.
</code>

===== See also =====

  * $lfn[llLog10] to calculate the logarithm in base 10.
  * $lfn[llPow] to raise a number to a power (also called antilogarithm).
  * $lty[float] type and associated caveats and limitations.