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#### 10.4.3 Division of `poly_int`s

Division of `poly_int`s is possible for certain inputs. The functions for division return true if the operation is possible and in most cases return the results by pointer. The routines are:

``multiple_p (a, b)`'
``multiple_p (a, b, &quotient)`'
  Return true if a is an exact multiple of b, storing the result in quotient if so. There are overloads for various combinations of polynomial and constant a, b and quotient.
``constant_multiple_p (a, b)`'
``constant_multiple_p (a, b, &quotient)`'
  Like `multiple_p`, but also test whether the multiple is a compile-time constant.
``can_div_trunc_p (a, b, &quotient)`'
``can_div_trunc_p (a, b, &quotient, &remainder)`'
  Return true if we can calculate ``trunc (a / b)`' at compile time, storing the result in quotient and remainder if so.
``can_div_away_from_zero_p (a, b, &quotient)`'
  Return true if we can calculate ``a / b`' at compile time, rounding away from zero. Store the result in quotient if so.

  Note that this is true if and only if `can_div_trunc_p` is true. The only difference is in the rounding of the result.

There is also an asserting form of division:

``exact_div (a, b)`'
  Assert that a is a multiple of b and return ``a / b`'. The result is a `poly_int` if a is a `poly_int`.