CppAD: A C++ Algorithmic Differentiation Package 20110419
sub.hpp
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00001 /* $Id$ */
00002 # ifndef CPPAD_SUB_INCLUDED
00003 # define CPPAD_SUB_INCLUDED
00004 
00005 /* --------------------------------------------------------------------------
00006 CppAD: C++ Algorithmic Differentiation: Copyright (C) 2003-11 Bradley M. Bell
00007 
00008 CppAD is distributed under multiple licenses. This distribution is under
00009 the terms of the 
00010                     Common Public License Version 1.0.
00011 
00012 A copy of this license is included in the COPYING file of this distribution.
00013 Please visit http://www.coin-or.org/CppAD/ for information on other licenses.
00014 -------------------------------------------------------------------------- */
00015 
00016 //  BEGIN CppAD namespace
00017 namespace CppAD {
00018 
00019 template <class Base>
00020 AD<Base> operator - (const AD<Base> &left , const AD<Base> &right)
00021 {       ADTape<Base> *tape = AD<Base>::tape_ptr();
00022         size_t tape_id = 0;
00023         if( tape != CPPAD_NULL )
00024                 tape_id = tape->id_;
00025 
00026         // id_ setting for parameters cannot match 0
00027         bool var_left  = left.id_  == tape_id;
00028         bool var_right = right.id_ == tape_id;
00029         CPPAD_ASSERT_KNOWN(
00030                 Parameter(left) || var_left ,
00031                 "-: left operand is a variable for a different thread"
00032         );
00033         CPPAD_ASSERT_KNOWN(
00034                 Parameter(right) || var_right ,
00035                 "-: right operand is a variable for a different thread"
00036         );
00037 
00038         AD<Base> result;
00039         result.value_  = left.value_ - right.value_;
00040         CPPAD_ASSERT_UNKNOWN( Parameter(result) );
00041 
00042         if( var_left )
00043         {       if( var_right )
00044                 {       // result = variable - variable
00045                         CPPAD_ASSERT_UNKNOWN( NumRes(SubvvOp) == 1 );
00046                         CPPAD_ASSERT_UNKNOWN( NumArg(SubvvOp) == 2 );
00047 
00048                         // put operand addresses in tape
00049                         tape->Rec_.PutArg(left.taddr_, right.taddr_);
00050                         // put operator in the tape
00051                         result.taddr_ = tape->Rec_.PutOp(SubvvOp);
00052                         // make result a variable
00053                         result.id_ = tape_id;
00054                 }
00055                 else if( IdenticalZero(right.value_) )
00056                 {       // result = variable - 0
00057                         result.make_variable(left.id_, left.taddr_);
00058                 }
00059                 else
00060                 {       // result = variable - parameter
00061                         CPPAD_ASSERT_UNKNOWN( NumRes(SubvpOp) == 1 );
00062                         CPPAD_ASSERT_UNKNOWN( NumArg(SubvpOp) == 2 );
00063 
00064                         // put operand addresses in tape
00065                         size_t p = tape->Rec_.PutPar(right.value_);
00066                         tape->Rec_.PutArg(left.taddr_, p);
00067                         // put operator in the tape
00068                         result.taddr_ = tape->Rec_.PutOp(SubvpOp);
00069                         // make result a variable
00070                         result.id_ = tape_id;
00071                 }
00072         }
00073         else if( var_right )
00074         {       // result = parameter - variable
00075                 CPPAD_ASSERT_UNKNOWN( NumRes(SubpvOp) == 1 );
00076                 CPPAD_ASSERT_UNKNOWN( NumArg(SubpvOp) == 2 );
00077 
00078                 // put operand addresses in tape
00079                 size_t p = tape->Rec_.PutPar(left.value_);
00080                 tape->Rec_.PutArg(p, right.taddr_);
00081                 // put operator in the tape
00082                 result.taddr_ = tape->Rec_.PutOp(SubpvOp);
00083                 // make result a variable
00084                 result.id_ = tape_id;
00085         }
00086         return result;
00087 }
00088 
00089 // convert other cases into the case above
00090 CPPAD_FOLD_AD_VALUED_BINARY_OPERATOR(-)
00091 
00092 } // END CppAD namespace
00093 
00094 # endif