\(\newcommand{\W}[1]{ \; #1 \; }\) \(\newcommand{\R}[1]{ {\rm #1} }\) \(\newcommand{\B}[1]{ {\bf #1} }\) \(\newcommand{\D}[2]{ \frac{\partial #1}{\partial #2} }\) \(\newcommand{\DD}[3]{ \frac{\partial^2 #1}{\partial #2 \partial #3} }\) \(\newcommand{\Dpow}[2]{ \frac{\partial^{#1}}{\partial {#2}^{#1}} }\) \(\newcommand{\dpow}[2]{ \frac{ {\rm d}^{#1}}{{\rm d}\, {#2}^{#1}} }\)
print_for_cout.cpp¶
View page sourcePrinting During Forward Mode: Example and Test¶
Running¶
To build this program and run its correctness test see cmake_check .
Source Code¶
# include <cppad/cppad.hpp>
namespace {
using std::cout;
using std::endl;
using CppAD::AD;
// use of PrintFor to check for invalid function arguments
AD<double> check_log(const AD<double>& y)
{ // check during recording
if( y <= 0. )
cout << "check_log: y = " << y << " is <= 0" << endl;
// check during zero order forward calculation
PrintFor(y, "check_log: y == ", y , " which is <= 0\n");
return log(y);
}
}
void print_for(void)
{ using CppAD::PrintFor;
// independent variable vector
size_t n = 1;
CPPAD_TESTVECTOR(AD<double>) ax(n);
ax[0] = 1.;
Independent(ax);
// print a VecAD<double>::reference object that is a parameter
CppAD::VecAD<double> av(1);
AD<double> Zero(0);
av[Zero] = 0.;
PrintFor("v[0] = ", av[Zero]);
// Print a newline to separate this from previous output,
// then print an AD<double> object that is a variable.
PrintFor("\nv[0] + x[0] = ", av[0] + ax[0]);
// A conditional print that will not generate output when x[0] = 2.
PrintFor(ax[0], "\n 2. + x[0] = ", 2. + ax[0], "\n");
// A conditional print that will generate output when x[0] = 2.
PrintFor(ax[0] - 2., "\n 3. + x[0] = ", 3. + ax[0], "\n");
// A log evaluations that will result in an error message when x[0] = 2.
AD<double> var = 2. - ax[0];
AD<double> log_var = check_log(var);
// dependent variable vector
size_t m = 2;
CPPAD_TESTVECTOR(AD<double>) ay(m);
ay[0] = av[Zero] + ax[0];
// define f: x -> y and stop tape recording
CppAD::ADFun<double> f(ax, ay);
// zero order forward with x[0] = 2
CPPAD_TESTVECTOR(double) x(n);
x[0] = 2.;
cout << "v[0] = 0" << endl;
cout << "v[0] + x[0] = 2" << endl;
cout << " 3. + x[0] = 5" << endl;
cout << "check_log: y == 0 which is <= 0" << endl;
// ./makefile.am expects "Test passes" at beginning of next output line
cout << "Test passes if four lines above repeat below:" << endl;
f.Forward(0, x);
return;
}
int main(void)
{ print_for();
return 0;
}
Output¶
Executing the program above generates the following output:
v[0] = 0
v[0] + x[0] = 2
Test passes if two lines above repeat below:
v[0] = 0
v[0] + x[0] = 2