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# Perl | log() Function

• Last Updated : 25 Jun, 2019

log() function in Perl returns the natural logarithm of value passed to it. Returns \$_ if called without passing a value. log() function can be used to find the log of any base by using the formula: Syntax: log(value)

Parameter:
value: Number of which log is to be calculated

Returns:
Floating point number in scalar context

Example 1:

 `#!/usr/bin/perl -w`` ` `# Calculating log of base 10 ``# using log function``print` `"log10(2): "``, log10(2), ``"\n"``;``print` `"log10(7): "``, log10(7), ``"\n"``;``print` `"log10(9): "``, log10(9), ``"\n"``;`` ` `# Function for log10 calculator``sub` `log10 ``{``    ``my` `\$n` `= ``shift``;``     ` `    ``# using pre-defined log function``    ``return` `log``(``\$n``) / ``log``(10);``}`

Output:

```log10(2): 0.301029995663981
log10(7): 0.845098040014257
log10(9): 0.954242509439325
```

Example 2:

 `#!/usr/bin/perl -w`` ` `# Calculating log of different ``# base using log function``print` `"log3(2): "``, log3(2), ``"\n"``;``print` `"log5(7): "``, log5(7), ``"\n"``;``print` `"log2(9): "``, log2(9), ``"\n"``;`` ` `# Function for log3 calculator``sub` `log3 ``{``    ``my` `\$n` `= ``shift``;``     ` `    ``# using pre-defined log function``    ``return` `log``(``\$n``) / ``log``(3);``}`` ` `# Function for log5 calculator``sub` `log5``{``    ``my` `\$n` `= ``shift``;``     ` `    ``# using pre-defined log function``    ``return` `log``(``\$n``) / ``log``(5);``}`` ` `# Function for log2 calculator``sub` `log2 ``{``    ``my` `\$n` `= ``shift``;``     ` `    ``# using pre-defined log function``    ``return` `log``(``\$n``) / ``log``(2);``}`

Output:

```log3(2): 0.630929753571457
log5(7): 1.20906195512217
log2(9): 3.16992500144231
```

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