Citation:
NUMBERS
The most basic element in bc is the number. Numbers are arbitrary precision numbers. This precision is both in the integer part and
the fractional part. All numbers are represented internally in decimal and all computation is done in decimal. (This version trun-
cates results from divide and multiply operations.) There are two attributes of numbers, the length and the scale. The length is the
total number of significant decimal digits in a number and the scale is the total number of decimal digits after the decimal point.
For example:
.000001 has a length of 6 and scale of 6.
1935.000 has a length of 7 and a scale of 3.
VARIABLES
Numbers are stored in two types of variables, simple variables and arrays. Both simple variables and array variables are named. Names
begin with a letter followed by any number of letters, digits and underscores. All letters must be lower case. (Full alpha-numeric
names are an extension. In POSIX bc all names are a single lower case letter.) The type of variable is clear by the context because
all array variable names will be followed by brackets ([]).
There are four special variables, scale, ibase, obase, and last. scale defines how some operations use digits after the decimal point.
The default value of scale is 0. ibase and obase define the conversion base for input and output numbers. The default for both input
and output is base 10. last (an extension) is a variable that has the value of the last printed number. These will be discussed in
further detail where appropriate. All of these variables may have values assigned to them as well as used in expressions.
