z/OS V1R9.0 UNIX System Services Command ... - Christian Grothoff

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Bases
The maximum value for scale is given by the configuration variable
{BC_SCALE_MAX} and the minimum value is 0.
bc lets you specify numbers in different bases—for example, octal (base 8) or
hexadecimal (base 16). You can input numbers in one base and output them in a
different base, simplifying the job of converting from one base to another. bc does
this using the built-in variables ibase and obase.
ibase is the base for input numbers. It has an initial value of 10 (normal decimal
numbers). To use a different base for inputting numbers, assign an integer to ibase,
as in:
ibase = 8
This means that all future input numbers are to be in base 8 (octal). The largest
valid input base is 16, and the smallest valid input base is 2. There is no
mechanism provided to represent digits larger than 15, so bases larger than 16 are
essentially useless. When the base is greater than 10, use the uppercase letters as
digits. For example, base 16 uses the digits 0 through 9, and A through F. The digits
are allowed in any number, regardless of the setting of ibase but are largely
meaningless if the base is smaller than the digit. The one case where this is useful
is in resetting the input base to 10. The constant A always has the value 10 no
matter what ibase is set to, so to reset the input base to 10, type:
ibase = A
obase is the base in which numbers are output. It has an initial value of 10 (normal
decimal numbers). To change output bases, assign an appropriate integer to obase.
If the output base is 16 or less, bc displays numbers with normal digits and
hexadecimal digits (if needed). The output base can also be greater than 16, in
which case each digit is printed as a decimal value and digits are separated by a
single space. For example, if obase is 1000, the decimal number 123 456 789 is
printed as:
123 456 789
Here, the digits are decimal values from 0 through 999. As a result, all output values
are broken up into one or more chunks with three digits per chunk. Using output
bases that are large powers of 10, you can arrange your output in columns; for
example, many users find that 100 000 makes a good output base, because
numbers are grouped into chunks of five digits each.
Long numbers are output with a maximum of 70 characters per line. If a number is
longer than this, bc puts a backslash (\) at the end of the line indicating that the
number is continued on the next line. The backslash (\) and newline characters are
counted as part of the 70 character length.
Internal calculations are performed in decimal, regardless of the input and output
bases. Therefore the number of places after the decimal point are dictated by the
scale when numbers are expressed in decimal form.
The maximum value for obase is given by the configuration variable
{BC_BASE_MAX}.
bc
Chapter 2. Shell command descriptions 53