Questions tagged [bc]

bc, for basic calculator, is "an arbitrary-precision calculator language" using algebraic infix notation. bc is typically used as either a mathematical scripting language or as an interactive mathematical shell.

Typical Usages

There are two ways bc is typically used.

• From a Unix command prompt, then interactively entering a mathematical expressions, such as (1 + 3) * 2, which will display 8.

• From the shell command prompt, where bc reads from standard input. For example $ echo '(1 + 3) * 2' | bc will display 8 in the shell.

While bc can perform calculations to arbitrary precision, its default behavior is to truncate calculations to whole numbers. I.e. entering the expression 2/3 displays 0. This can surprise new bc users. The number of digits that bc displays is determined by a variable scale, which may be changed. For example, running bc interactively, setting scale=7 then entering 2/3 will display .6666666. Starting bc with the -l option loads a math library, setting scale to 20 and loading these math functions

s (x)    The sine of x, x is in radians.
c (x)    The cosine of x, x is in radians.
a (x)    The arctangent of x, arctangent returns radians.
l (x)    The natural logarithm of x.
e (x)    The exponential function of raising e to the value x.
j (n,x)  The bessel function of integer order n of x.

In 1991, POSIX rigorously defined and standardized bc. Two implementations of that standard survive today:

1. Traditional bc, on Unix and Plan 9 systems.

2. GNU bc with numerous extensions beyond the POSIX standard, on Linux, etc.

Links & References

• GNU bc Manual

• bc (programming language) Wikipedia Article

• phodd.net/gnu-bc, a large collection of bc scripts

• POSIX bc specification from The Open Group Library