# IT. Expert System.

## C

### log()

log function returns natural logarithm (base is e) of a number, where e is the exponential number.

Syntax:
`double log(double);`

Example:

```#include
#include

int main()
{
double n, result;

printf("Enter a number to calculate it's natural log (base is e)\n");
scanf("%lf", &n);

result = log(n);

printf("Natural log of %.2lf = %lf\n", n, result);

return 0;
}```

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