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234 lines
6.0 KiB
234 lines
6.0 KiB
// $Id: time_test.hpp 3855 2016-12-19 00:30:54Z bradbell $
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# ifndef CPPAD_UTILITY_TIME_TEST_HPP
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# define CPPAD_UTILITY_TIME_TEST_HPP
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/* --------------------------------------------------------------------------
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CppAD: C++ Algorithmic Differentiation: Copyright (C) 2003-16 Bradley M. Bell
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CppAD is distributed under multiple licenses. This distribution is under
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the terms of the
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Eclipse Public License Version 1.0.
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A copy of this license is included in the COPYING file of this distribution.
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Please visit http://www.coin-or.org/CppAD/ for information on other licenses.
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-------------------------------------------------------------------------- */
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/*
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$begin time_test$$
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$spell
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gettimeofday
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vec
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cppad.hpp
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Microsoft
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namespace
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std
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const
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cout
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ctime
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ifdef
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const
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endif
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cpp
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$$
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$section Determine Amount of Time to Execute a Test$$
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$mindex time_test speed$$
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$head Syntax$$
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$codei%# include <cppad/utility/time_test.hpp>
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%$$
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$icode%time% = time_test(%test%, %time_min%)
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%$$
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$icode%time% = time_test(%test%, %time_min%, %test_size%)%$$
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$head Purpose$$
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The $code time_test$$ function executes a timing test
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and reports the amount of wall clock time for execution.
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$head Motivation$$
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It is important to separate small calculation units
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and test them individually.
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This way individual changes can be tested in the context of the
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routine that they are in.
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On many machines, accurate timing of a very short execution
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sequences is not possible.
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In addition,
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there may be set up and tear down time for a test that
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we do not really want included in the timing.
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For this reason $code time_test$$
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automatically determines how many times to
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repeat the section of the test that we wish to time.
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$head Include$$
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The file $code cppad/time_test.hpp$$ defines the
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$code time_test$$ function.
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This file is included by $code cppad/cppad.hpp$$
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and it can also be included separately with out the rest of
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the $code CppAD$$ routines.
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$head test$$
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The $code time_test$$ argument $icode test$$ is a function,
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or function object.
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In the case where $icode test_size$$ is not present,
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$icode test$$ supports the syntax
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$codei%
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%test%(%repeat%)
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%$$
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In the case where $icode test_size$$ is present,
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$icode test$$ supports the syntax
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$codei%
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%test%(%size%, %repeat%)
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%$$
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In either case, the return value for $icode test$$ is $code void$$.
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$subhead size$$
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If the argument $icode size$$ is present,
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it has prototype
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$codei%
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size_t %size%
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%$$
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and is equal to the $icode test_size$$ argument to $code time_test$$.
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$subhead repeat$$
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The $icode test$$ argument $icode repeat$$ has prototype
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$codei%
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size_t %repeat%
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%$$
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It will be equal to the $icode size$$ argument to $code time_test$$.
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$head time_min$$
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The argument $icode time_min$$ has prototype
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$codei%
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double %time_min%
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%$$
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It specifies the minimum amount of time in seconds
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that the $icode test$$ routine should take.
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The $icode repeat$$ argument to $icode test$$ is increased
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until this amount of execution time (or more) is reached.
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$head test_size$$
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This argument has prototype
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$codei%
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size_t %test_size%
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%$$
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It specifies the $icode size$$ argument to $icode test$$.
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$head time$$
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The return value $icode time$$ has prototype
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$codei%
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double %time%
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%$$
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and is the number of wall clock seconds that it took
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to execute $icode test$$ divided by the value used for $icode repeat$$.
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$head Timing$$
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The routine $cref elapsed_seconds$$ will be used to determine the
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amount of time it took to execute the test.
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$children%
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cppad/utility/elapsed_seconds.hpp%
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speed/example/time_test.cpp
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%$$
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$head Example$$
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The routine $cref time_test.cpp$$ is an example and test
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of $code time_test$$.
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$end
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-----------------------------------------------------------------------
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*/
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# include <algorithm>
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# include <cstddef>
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# include <cmath>
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# include <cppad/utility/elapsed_seconds.hpp>
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# include <cppad/core/define.hpp>
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# define CPPAD_EXTRA_RUN_BEFORE_TIMING 0
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namespace CppAD { // BEGIN_CPPAD_NAMESPACE
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/*!
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\file time_test.hpp
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\brief Function that preforms one timing test (for speed of execution).
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*/
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/*!
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Preform one wall clock execution timing test.
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\tparam Test
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Either the type <code>void (*)(size_t)</code> or a function object
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type that supports the same syntax.
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\param test
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The function, or function object, that supports the operation
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<code>test(repeat)</code> where \c repeat is the number of times
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to repeat the tests operaiton that is being timed.
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\param time_min
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is the minimum amount of time that \c test should take to preform
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the repetitions of the operation being timed.
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*/
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template <class Test>
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double time_test(Test test, double time_min )
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{
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# if CPPAD_EXTRA_RUN_BEFORE_TIMING
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test(1);
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# endif
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size_t repeat = 0;
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double s0 = elapsed_seconds();
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double s1 = s0;
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while( s1 - s0 < time_min )
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{ repeat = std::max(size_t(1), 2 * repeat);
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s0 = elapsed_seconds();
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test(repeat);
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s1 = elapsed_seconds();
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}
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double time = (s1 - s0) / double(repeat);
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return time;
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}
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/*!
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Preform one wall clock execution timing test.
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\tparam Test
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Either the type <code>void (*)(size_t, size_t)</code> or a function object
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type that supports the same syntax.
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\param test
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The function, or function object, that supports the operation
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<code>test(size, repeat)</code> where
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\c is the size for this test and
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\c repeat is the number of times
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to repeat the tests operaiton that is being timed.
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\param time_min
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is the minimum amount of time that \c test should take to preform
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the repetitions of the operation being timed.
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\param test_size
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will be used for the value of \c size in the call to \c test.
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*/
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template <class Test>
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double time_test(Test test, double time_min, size_t test_size)
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{
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# if CPPAD_EXTRA_RUN_BEFORE_TIMING
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test(test_size, 1);
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# endif
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size_t repeat = 0;
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double s0 = elapsed_seconds();
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double s1 = s0;
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while( s1 - s0 < time_min )
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{ repeat = std::max(size_t(1), 2 * repeat);
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s0 = elapsed_seconds();
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test(test_size, repeat);
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s1 = elapsed_seconds();
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}
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double time = (s1 - s0) / double(repeat);
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return time;
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}
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} // END_CPPAD_NAMESPACE
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# undef CPPAD_EXTRA_RUN_BEFORE_TIMING
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// END PROGRAM
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# endif
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