\(\newcommand{\W}[1]{ \; #1 \; }\) \(\newcommand{\R}[1]{ {\rm #1} }\) \(\newcommand{\B}[1]{ {\bf #1} }\) \(\newcommand{\D}[2]{ \frac{\partial #1}{\partial #2} }\) \(\newcommand{\DD}[3]{ \frac{\partial^2 #1}{\partial #2 \partial #3} }\) \(\newcommand{\Dpow}[2]{ \frac{\partial^{#1}}{\partial {#2}^{#1}} }\) \(\newcommand{\dpow}[2]{ \frac{ {\rm d}^{#1}}{{\rm d}\, {#2}^{#1}} }\)

speed_program.cpp

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Example Use of SpeedTest

Program

# include <cppad/utility/speed_test.hpp>

// Some compilers have gotten smarter and do not calculate something that is not used
// so make the result a global.
double global_result = 0.0;

std::string Test(size_t size, size_t repeat)
{  // setup
    double *a = new double[size];
    double *b = new double[size];
    size_t i  = size;;
    while(i)
    {  --i;
        a[i] = double(i);
        b[i] = double(2 * i);
    }
    // operations we are timing
    while(repeat--)
    {  i = size;;
        while(i)
        {  --i;
            global_result += a[i] * b[i];
        }
    }
    // teardown
    delete [] a;
    delete [] b;

    // return a test name that is valid for all sizes and repeats
    return "double: result = sum_i a[i] * b[i]";
}
int main(void)
{
    CppAD::SpeedTest(Test, 20, 20, 100);
    return 0;
}

Output

Executing of the program above generated the following output (the rates will be different for each particular system):

double: c[*] = a[*] + b[*]
size = 20  rate = 7,157,515
size = 40  rate = 3,887,214
size = 60  rate = 2,685,214
size = 80  rate = 2,032,124
size = 100 rate = 1,657,828