# 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 functionprint "log10(2): ", log10(2), "\n";print "log10(7): ", log10(7), "\n";print "log10(9): ", log10(9), "\n";  # Function for log10 calculatorsub 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 functionprint "log3(2): ", log3(2), "\n";print "log5(7): ", log5(7), "\n";print "log2(9): ", log2(9), "\n";  # Function for log3 calculatorsub log3 {    my \$n = shift;          # using pre-defined log function    return log(\$n) / log(3);}  # Function for log5 calculatorsub log5{    my \$n = shift;          # using pre-defined log function    return log(\$n) / log(5);}  # Function for log2 calculatorsub 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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