The `log10`

function in `math.h`

is behaving differently from what I expected.

My understanding is that log10(10000) will produce a result of **4** but I get **2.0553e-320**

This is my code:

```
#include <math.h>
double result = 0;
void setup()
{
Spark.variable("result", &result, DOUBLE);
}
void loop()
{
result = log10(10000);
delay(500);
}
```

Why I am not getting 4 as answer?