# llLog

*LSL function*

```lsl
float float llLog(float val);
```

- `float val`: Number to compute the logarithm of.

- Returns: `float`
- Energy: 10

To get the base 10 logarithm use [llLog10](/functions/llLog10/).

Returns a [float](https://wiki.secondlife.com/wiki/float) that is the [natural logarithm](https://en.wikipedia.org/wiki/natural_logarithm) of **val**.

If **val** <= 0 return 0.0 instead.

```lsl title="How to use" frame="terminal"
float result = llLog(0.0);
```

## Examples

<details open>
<summary>Example 1</summary>

```lsl
default
{
  state_entry()
  {
    float num1 = llFrand(100.0);

    llOwnerSay("The natural logarithm of " + (string)num1 + " is " + (string)llLog(num1));
  }
}
```

</details>

<details>
<summary>Example 2</summary>

```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
    }
}
```

</details>

## Notes

There are only two log functions [llLog](/functions/llLog/) and [llLog10](/functions/llLog10/). Errors introduced as a result of floating-point arithmetic are most noticable when working with logarithms. [llLog](/functions/llLog/) should be used instead of [llLog10](/functions/llLog10/) when converting the base of the logarithm.

```lsl
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 |  |
| 4 |  |
| 8 |  |
| 10 |  |
| 16 |  |
| 32 |  |
| 64 |  |
| 128 |  |
| 256 |  |

## See also

### Functions

- [llLog10](/functions/llLog10/)
- [llPow](/functions/llPow/)
- [llSqrt](/functions/llSqrt/)

### Articles

- [Natural logarithm](https://en.wikipedia.org/wiki/Natural_logarithm)

---

*Source: [LlLog](https://wiki.secondlife.com/wiki/LlLog) on the Second Life Wiki. Content from the Second Life Wiki article LlLog (revision 1194348, 2015-01-22), CC BY-SA 3.0.*

---

From lsl.dev: https://lsl.dev/functions/llLog/