The BOOST_PP_MUL_D macro expands to the product of its second and third arguments. It reenters BOOST_PP_WHILE with maximum efficiency.

#### Usage

BOOST_PP_MUL_D(d, x, y)

#### Arguments

d
  The next available BOOST_PP_WHILE iteration.
x
  The multiplicand of the operation. Valid values range from 0 to BOOST_PP_LIMIT_MAG.
y
  The multiplier of the operation. Valid values range from 0 to BOOST_PP_LIMIT_MAG.

#### Remarks

If the product of x and y is greater than BOOST_PP_LIMIT_MAG, the result is saturated to BOOST_PP_LIMIT_MAG.
This macro is the most efficient when x is less than or equal to y. However, the efficiency gain is not worth actually comparing the two arguments prior to invocation. In other words, x should be the value that is most likely to be the largest of the two operands.

#### See Also

- BOOST_PP_LIMIT_MAG
- BOOST_PP_MUL

#### Requirements

Header: <boost/preprocessor/arithmetic/mul.hpp>

#### Sample Code

    #include <boost/preprocessor/arithmetic/dec.hpp>
    #include <boost/preprocessor/arithmetic/mul.hpp>
    #include <boost/preprocessor/control/while.hpp>
    #include <boost/preprocessor/tuple/elem.hpp>

    #define PRED(d, data) BOOST_PP_TUPLE_ELEM(3, 0, data)

    #define OP(d, data) \
       ( \
          BOOST_PP_DEC( \
             BOOST_PP_TUPLE_ELEM(3, 0, data) \
          ), \
          BOOST_PP_TUPLE_ELEM(3, 1, data), \
          BOOST_PP_MUL_D( \
             d, \
             BOOST_PP_TUPLE_ELEM(3, 2, data), \
             BOOST_PP_TUPLE_ELEM(3, 1, data) \
          ) \
       ) \
       /**/

    // raise 'x' to the 'n'-th power
    #define EXP(x, n) BOOST_PP_TUPLE_ELEM(3, 2, BOOST_PP_WHILE(PRED, OP, (n, x, 1)))

    EXP(4, 2) // expands to 16
    EXP(2, 3) // expands to 8