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// Under terms of Contract DE-AC04-94AL85000, there is a non-exclusive
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// This library is free software; you can redistribute it and/or modify
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// Lesser General Public License for more details.
//
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// License along with this library; if not, write to the Free Software
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#ifdef HAVE_MPI
#include "mpi.h"
#endif

#include "Teuchos_ParameterList.hpp"
#include "Teuchos_ConfigDefs.hpp"

int main(int argc, char* argv[])
{
#ifdef HAVE_MPI
MPI_Init(&argc,&argv);
#endif

// Creating an empty parameter list looks like:
Teuchos::ParameterList My_List;

// Setting parameters in this list can be easily done:
My_List.set("Max Iters", 1550);
My_List.set("Tolerance", 1e-10);
My_List.set("Solver", "GMRES");

/* The templated set'' method should cast the input {\it value} to the
correct data type.  However, in the case where the compiler is not casting the input
value to the expected data type, an explicit cast can be used with the set'' method:
*/
My_List.set("Tolerance", (float)(1e-10));

/* A hierarchy of parameter lists can be constructed using {\tt Teuchos::ParameterList}.  This
means another parameter list is a valid {\it value} in any parameter list.  To create a sublist
in a parameter list and obtain a reference to it:
*/
Teuchos::ParameterList& Prec_List = My_List.sublist("Preconditioner");

// Now this parameter list can be filled with values:
Prec_List.set("Type", "ILU");
Prec_List.set("Drop Tolerance", 1e-3);

// The parameter list can be queried about the existance of a parameter, sublist, or type:
// Has a solver been chosen?
bool solver_defined, prec_defined, tol_double, dtol_double;
solver_defined = My_List.isParameter("Solver");
// Has a preconditioner been chosen?
prec_defined = My_List.isSublist("Preconditioner");
// Has a tolerance been chosen and is it a double-precision number?
tol_double = My_List.INVALID_TEMPLATE_QUALIFIER isType<double>("Tolerance");
// Has a drop tolerance been chosen and is it a double-precision number?
dtol_double = Teuchos::isParameterType<double>(Prec_List, "Drop Tolerance");

/* The last two methods for checking the parameter type are equivalent.
There is some question as to whether the syntax of the first type-checking
method is acceptable to older compilers.  Thus, the second type-checking method
is offered as a portable alternative.
*/
// Parameters can be retrieved from the parameter list in quite a few ways:
// Get method that creates and sets the parameter if it doesn't exist.
int its;
its = My_List.get("Max Iters", 1200);
// Get method that retrieves a parameter of a particular type.
float tol;
tol = My_List.INVALID_TEMPLATE_QUALIFIER get<float>("Tolerance");

/* In the above example, the first get'' method is a safe way of
obtaining a parameter when its existence is indefinite but required.
The second get'' method should be used when the existense of the parameter
is definite.  This method will throw an exception if the parameter doesn't exist.
The safest way to use the second get'' method
is in a try/catch block:
*/
try {
tol = My_List.INVALID_TEMPLATE_QUALIFIER get<float>("Tolerance");
}
catch (std::exception& e) {
tol = 1e-6;
}

/* The second get'' method uses a syntax that may not be
acceptable to older compilers.  Optionally, there is another portable templated
get'' function that can be used in the place of the second get'' method:
*/
try {
tol = Teuchos::getParameter<float>(My_List, "Tolerance");
}
catch (std::exception& e) {
tol = 1e-6;
}

// A parameter list can be sent to the output stream:
cout<< My_List << endl;

/* It is important to note that mispelled parameters
(with additional space characters, capitalizations, etc.) may be ignored.
Therefore, it is important to be aware that a given parameter has not been used.
Unused parameters can be printed with method:
*/
My_List.unused( cout );

#ifdef HAVE_MPI
MPI_Finalize();
#endif
return 0;
}

#else

#include <stdlib.h>
#include <stdio.h>

int main(int argc, char *argv[])
{
#ifdef HAVE_MPI
MPI_Init(&argc,&argv);
#endif