How do I calculate the log of a number using bc?

unix bc
Bruce picture Bruce · Nov 1, 2011 · Viewed 38.3k times · Source

This is the first time I am using bc. I want to calculate the log (base 10) of a number. How do I this?

Answer

Ray Toal picture Ray Toal · Nov 1, 2011

Invoke bc with the -l option (to enable the math library) like so

$ echo 'l(100)/l(10)' | bc -l
2.00000000000000000000

Use the l function which is the natural log. Take the log of the number you are interested in then divide by the natural log of 10.

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