# Perl ABC

1. Perl
2. builtin functions
3. here

## log function - find logarithm

You can use the log function to find the natural logarithm. You can also use the base transformation to calculate the logarithm of any base.

#### Find the natural logarithm

Use the log function to find the natural logarithm. The natural logarithm is the logarithm whose base is the Napier number e.

```log(10);
```

#### Find the common logarithm

The common logarithm is a logarithm with a base of 10. You can use the logarithms change formula to find the logarithm of any base.

```sub log10 {
my \$x = shift;
return log(\$x)/log(10);
}
```

### Example program

This is an example to find the logarithm using the log function.

```use strict;
use warnings;

# The base of the logarithm is the Napier number e;
print "(1) Natural logarithm\n";
print "log(3) =" . Log (10). "\n\n";

print "(2) Common logarithm\n";
print "log10 (100) =" . Log10 (100) . "\n";

# A function to find the logarithm with a base of 10 (using the logarithms of the base)
sub log10 {
my \$x = shift;
return log(\$x)/log(10);
}
```