lines 195-348 of file: include/cppad/utility/speed_test.hpp

{xrst_begin SpeedTest}
{xrst_spell
   cout
   ctime
}

Run One Speed Test and Print Results
####################################

Syntax
******

   # ``include <cppad/utility/speed_test.hpp>``

``SpeedTest`` ( *Test* , *first* , *inc* , *last* )

See Also
********
:ref:`time_test-name`

Purpose
*******
The ``SpeedTest`` function executes a speed test
for various sized problems
and reports the results on standard output; i.e. ``std::cout`` .
The size of each test problem is included in its report
(unless *first* is equal to *last* ).

Motivation
**********
It is important to separate small calculation units
and test them individually.
This way individual changes can be tested in the context of the
routine that they are in.
On many machines, accurate timing of a very short execution
sequences is not possible.
In addition,
there may be set up time for a test that
we do not really want included in the timing.
For this reason ``SpeedTest``
automatically determines how many times to
repeat the section of the test that we wish to time.

Include
*******
The file ``speed_test.hpp`` contains the
``SpeedTest`` function.
This file is included by ``cppad/utility/cppad.hpp``
but it can also be included separately with out the rest of
the ``CppAD`` routines.

Test
****
The ``SpeedTest`` argument *Test* is a function with the syntax

   *name* = *Test* ( *size* , *repeat* )

size
====
The *Test* argument *size* has prototype

   ``size_t`` *size*

It specifies the size for this test.

repeat
======
The *Test* argument *repeat* has prototype

   ``size_t`` *repeat*

It specifies the number of times to repeat the test.

name
====
The *Test* result *name* has prototype

   ``std::string`` *name*

The results for this test are reported on ``std::cout``
with *name* as an identifier for the test.
It is assumed that,
for the duration of this call to ``SpeedTest`` ,
*Test* will always return
the same value for *name* .
If *name* is the empty string,
no test name is reported by ``SpeedTest`` .

first
*****
The ``SpeedTest`` argument *first* has prototype

   ``size_t`` *first*

It specifies the size of the first test problem reported by this call to
``SpeedTest`` .

last
****
The ``SpeedTest`` argument *last* has prototype

   ``size_t`` *last*

It specifies the size of the last test problem reported by this call to
``SpeedTest`` .

inc
***
The ``SpeedTest`` argument *inc* has prototype

   ``int`` *inc*

It specifies the increment between problem sizes; i.e.,
all values of *size* in calls to *Test* are given by

   *size* = *first* + *j* * *inc*

where *j* is a positive integer.
The increment can be positive or negative but it cannot be zero.
The values *first* , *last* and *inc* must
satisfy the relation

.. math::

   inc * ( last - first ) \geq 0

rate
****
The value displayed in the ``rate`` column on ``std::cout``
is defined as the value of *repeat* divided by the
corresponding elapsed execution time in seconds.
The elapsed execution time is measured by the difference in
::

   (double) clock() / (double) CLOCKS_PER_SEC

in the context of the standard ``<ctime>`` definitions.

Errors
******
If one of the restrictions above is violated,
the CppAD error handler is used to report the error.
You can redefine this action using the instructions in
:ref:`ErrorHandler-name`

Example
*******
{xrst_toc_hidden
   speed/example/speed_program.cpp
}
The program :ref:`speed_program.cpp-name` is an example usage
of ``SpeedTest`` .

{xrst_end SpeedTest}