base_alloc.hpp¶

Example AD<Base> Where Base Constructor Allocates Memory¶

Purpose ¶

Demonstrate use of AD < Base > where memory is allocated for each element of the type Base . In addition, this is a complete example where all the required Base type operations are defined (as apposed to other examples where some of the operations for the Base type are already defined).

Include File ¶

This file uses some of the definitions in base_require and thread_alloc .

# include <cppad/base_require.hpp>
# include <cppad/utility/thread_alloc.hpp>

Compound Assignment Macro ¶

This macro is used for the base_alloc compound assignment operators; to be specific, used with op equal to += , -= , *= , /= .

# define BASE_ALLOC_ASSIGN_OPERATOR(op) \
   void operator op (const base_alloc& x) \
   {  *ptrdbl_ op *x.ptrdbl_; }

Binary Operator Macro ¶

This macro is used for the base_alloc binary operators (as member functions); to be specific, used with op equal to + , - , * , / .

# define BASE_ALLOC_BINARY_OPERATOR(op) const \
   base_alloc operator op (const base_alloc& x) const \
   {  base_alloc result; \
      double   dbl = *ptrdbl_; \
      double x_dbl = *x.ptrdbl_; \
      *result.ptrdbl_ = dbl op x_dbl; \
      return result; \
   }

Boolean Operator Macro ¶

This macro can be used for the base_alloc binary operators that have a bool result; to be specific, used with op equal to == , != , < , <= , >= , and > ,

# define BASE_ALLOC_BOOL_OPERATOR(op) const \
   bool operator op (const base_alloc& x) const \
   {  double   dbl = *ptrdbl_; \
      double x_dbl = *x.ptrdbl_; \
      return dbl op x_dbl; \
   }

Class Definition ¶

The following example class defines the necessary base_member functions. It is made more complicated by storing a pointer to a double instead of the double value itself.

class base_alloc {
public:
   double* ptrdbl_;

   base_alloc(void)
   {  size_t cap;
      void* v  = CppAD::thread_alloc::get_memory(sizeof(double), cap);
      ptrdbl_  = static_cast<double*>(v);
   }
   base_alloc(double dbl)
   {  size_t cap;
      void *v  = CppAD::thread_alloc::get_memory(sizeof(double), cap);
      ptrdbl_  = static_cast<double*>(v);
      *ptrdbl_ = dbl;
   }
   base_alloc(const base_alloc& x)
   {  size_t cap;
      void *v  = CppAD::thread_alloc::get_memory(sizeof(double), cap);
      ptrdbl_  = static_cast<double*>(v);
      *ptrdbl_ = *x.ptrdbl_;
   }
   ~base_alloc(void)
   {  void* v  = static_cast<void*>(ptrdbl_);
      CppAD::thread_alloc::return_memory(v);
   }
   base_alloc operator-(void) const
   {  base_alloc result;
      *result.ptrdbl_ = - *ptrdbl_;
      return result;
   }
   base_alloc operator+(void) const
   {  return *this; }
   void operator=(const base_alloc& x)
   {  *ptrdbl_ = *x.ptrdbl_; }
   BASE_ALLOC_ASSIGN_OPERATOR(+=)
   BASE_ALLOC_ASSIGN_OPERATOR(-=)
   BASE_ALLOC_ASSIGN_OPERATOR(*=)
   BASE_ALLOC_ASSIGN_OPERATOR(/=)
   BASE_ALLOC_BINARY_OPERATOR(+)
   BASE_ALLOC_BINARY_OPERATOR(-)
   BASE_ALLOC_BINARY_OPERATOR(*)
   BASE_ALLOC_BINARY_OPERATOR(/)
   BASE_ALLOC_BOOL_OPERATOR(==)
   BASE_ALLOC_BOOL_OPERATOR(!=)
   // The <= operator is not necessary for the base type requirements
   // (needed so we can use NearEqual with base_alloc arguments).
   BASE_ALLOC_BOOL_OPERATOR(<=)
};

CondExpOp ¶

The type base_alloc does not use CondExp operations. Hence its CondExpOp function is defined by

namespace CppAD {
   inline base_alloc CondExpOp(
      enum CompareOp     cop          ,
      const base_alloc&       left         ,
      const base_alloc&       right        ,
      const base_alloc&       exp_if_true  ,
      const base_alloc&       exp_if_false )
   {  // not used
      assert(false);

      // to void compiler error
      return base_alloc();
   }
}

CondExpRel ¶

The CPPAD_COND_EXP_REL macro invocation

namespace CppAD {
   CPPAD_COND_EXP_REL(base_alloc)
}

uses CondExpOp above to define CondExp Rel for base_alloc arguments and Rel equal to Lt , Le , Eq , Ge , and Gt .

EqualOpSeq ¶

The type base_alloc is simple (in this respect) and so we define

namespace CppAD {
   inline bool EqualOpSeq(const base_alloc& x, const base_alloc& y)
   {  return *x.ptrdbl_ == *y.ptrdbl_; }
}

Identical ¶

The type base_alloc is simple (in this respect) and so we define

namespace CppAD {
   inline bool IdenticalCon(const base_alloc& x)
   {  return true; }
   inline bool IdenticalZero(const base_alloc& x)
   {  return (*x.ptrdbl_ == 0.0); }
   inline bool IdenticalOne(const base_alloc& x)
   {  return (*x.ptrdbl_ == 1.0); }
   inline bool IdenticalEqualCon(const base_alloc& x, const base_alloc& y)
   {  return (*x.ptrdbl_ == *y.ptrdbl_); }
}

Output Operator ¶

namespace CppAD {
   inline std::ostream& operator << (std::ostream &os, const base_alloc& x)
   {  os << *x.ptrdbl_;
      return os;
   }
}

Integer ¶

namespace CppAD {
   inline int Integer(const base_alloc& x)
   {  return static_cast<int>(*x.ptrdbl_); }
}

azmul ¶

namespace CppAD {
   CPPAD_AZMUL( base_alloc )
}

Ordered ¶

The base_alloc type supports ordered comparisons

namespace CppAD {
   inline bool GreaterThanZero(const base_alloc& x)
   {  return *x.ptrdbl_ > 0.0; }
   inline bool GreaterThanOrZero(const base_alloc& x)
   {  return *x.ptrdbl_ >= 0.0; }
   inline bool LessThanZero(const base_alloc& x)
   {  return *x.ptrdbl_ < 0.0; }
   inline bool LessThanOrZero(const base_alloc& x)
   {  return *x.ptrdbl_ <= 0.f; }
   inline bool abs_geq(const base_alloc& x, const base_alloc& y)
   {  return std::fabs(*x.ptrdbl_) >= std::fabs(*y.ptrdbl_); }
}

Unary Standard Math ¶

The macro CPPAD_STANDARD_MATH_UNARY would not work with the type base_alloc so we define a special macro for this type:

# define BASE_ALLOC_STD_MATH(fun) \
   inline base_alloc fun (const base_alloc& x) \
   { return   std::fun(*x.ptrdbl_); }

The following invocations of the macro above define the Unary Standard Math functions (except for abs ):

namespace CppAD {
   BASE_ALLOC_STD_MATH(acos)
   BASE_ALLOC_STD_MATH(acosh)
   BASE_ALLOC_STD_MATH(asin)
   BASE_ALLOC_STD_MATH(asinh)
   BASE_ALLOC_STD_MATH(atan)
   BASE_ALLOC_STD_MATH(atanh)
   BASE_ALLOC_STD_MATH(cos)
   BASE_ALLOC_STD_MATH(cosh)
   BASE_ALLOC_STD_MATH(erf)
   BASE_ALLOC_STD_MATH(erfc)
   BASE_ALLOC_STD_MATH(exp)
   BASE_ALLOC_STD_MATH(expm1)
   BASE_ALLOC_STD_MATH(fabs)
   BASE_ALLOC_STD_MATH(log)
   BASE_ALLOC_STD_MATH(log1p)
   BASE_ALLOC_STD_MATH(log10)
   BASE_ALLOC_STD_MATH(sin)
   BASE_ALLOC_STD_MATH(sinh)
   BASE_ALLOC_STD_MATH(sqrt)
   BASE_ALLOC_STD_MATH(tan)
   BASE_ALLOC_STD_MATH(tanh)
}

The absolute value function is special because it std name is fabs

namespace CppAD {
   inline base_alloc abs(const base_alloc& x)
   {  return fabs(*x.ptrdbl_); }
}

The isnan function is special because it returns a bool

namespace CppAD {
   inline bool isnan(const base_alloc& x)
   {  return *x.ptrdbl_ != *x.ptrdbl_; }
}

sign ¶

The following defines the CppAD::sign function that is required to use AD<base_alloc> :

namespace CppAD {
   inline base_alloc sign(const base_alloc& x)
   {  if( *x.ptrdbl_ > 0.0 )
         return 1.0;
      if( *x.ptrdbl_ == 0.0 )
         return 0.0;
      return -1.0;
   }
}

pow ¶

The following defines a CppAD::pow function that is required to use AD<base_alloc> :

namespace CppAD {
   inline base_alloc pow(const base_alloc& x, const base_alloc& y)
   { return std::pow(*x.ptrdbl_, *y.ptrdbl_); }
}

numeric_limits ¶

The following defines the CppAD numeric_limits for the type base_alloc :

namespace CppAD {
   CPPAD_NUMERIC_LIMITS(double, base_alloc)
}

to_string ¶

The following defines the CppAD to_string function for the type base_alloc :

namespace CppAD {
   CPPAD_TO_STRING(base_alloc)
}

hash_code ¶

The Default hashing function does not work well for this case because two different pointers can have the same value.

namespace CppAD {
   inline unsigned short hash_code(const base_alloc& x)
   {  unsigned short code = 0;
      if( *x.ptrdbl_ == 0.0 )
         return code;
      double log_x = log( std::fabs( *x.ptrdbl_ ) );
      // assume log( std::numeric_limits<double>::max() ) is near 700
      code = static_cast<unsigned short>(
         (CPPAD_HASH_TABLE_SIZE / 700 + 1) * log_x
      );
      code = code % CPPAD_HASH_TABLE_SIZE;
      return code;
   }
}