dc: Arithmetic
4 Arithmetic
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'+'
Pops two values off the stack, adds them, and pushes the result.
The precision of the result is determined only by the values of the
arguments, and is enough to be exact.
'-'
Pops two values, subtracts the first one popped from the second one
popped, and pushes the result.
'*'
Pops two values, multiplies them, and pushes the result. The
number of fraction digits in the result is the largest of the
precision value, the number of fraction digits in the multiplier,
or the number of fraction digits in the multiplicand; but in no
event exceeding the number of digits required for an exact result.
'/'
Pops two values, divides the second one popped from the first one
popped, and pushes the result. The number of fraction digits is
specified by the precision value.
'%'
Pops two values, computes the remainder of the division that the
'/' command would do, and pushes that. The value computed is the
same as that computed by the sequence 'Sd dld/ Ld*-' .
'~'
Pops two values, divides the second one popped from the first one
popped. The quotient is pushed first, and the remainder is pushed
next. The number of fraction digits used in the division is
specified by the precision value. (The sequence 'SdSn lnld/ LnLd%'
could also accomplish this function, with slightly different error
checking.) (This command is a GNU extension.)
'^'
Pops two values and exponentiates, using the first value popped as
the exponent and the second popped as the base. The fraction part
of the exponent is ignored. The precision value specifies the
number of fraction digits in the result.
'|'
Pops three values and computes a modular exponentiation. The first
value popped is used as the reduction modulus; this value must be a
non-zero number, and the result may not be accurate if the modulus
is not an integer. The second popped is used as the exponent; this
value must be a non-negative number, and any fractional part of
this exponent will be ignored. The third value popped is the base
which gets exponentiated, which should be an integer. For small
integers this is like the sequence 'Sm^Lm%', but, unlike '^', this
command will work with arbitrarily large exponents. (This command
is a GNU extension.)
'v'
Pops one value, computes its square root, and pushes that. The
maximum of the precision value and the precision of the argument is
used to determine the number of fraction digits in the result.
Most arithmetic operations are affected by the _precision value_,
which you can set with the 'k' command. The default precision value is
zero, which means that all arithmetic except for addition and
subtraction produces integer results.
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