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========= |
\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
\\ / O peration | Website: https://openfoam.org
\\ / A nd | Copyright (C) 2025-2026 OpenFOAM Foundation
\\/ M anipulation |
-------------------------------------------------------------------------------
License
This file is part of OpenFOAM.
OpenFOAM is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with OpenFOAM. If not, see <http://www.gnu.org/licenses/>.
Class
Foam::functionEntries::streamEntry
Description
Compiles and executes C++ OpenFOAM code string expressions
inserting the result into the dictionary or dictionary entry. The
functionality of \#stream is equivalent to \#codeStream but with a
simpler syntax, relying on separate \#codeInclude entries to provide
required include files. For more details see
Foam::functionEntries::codeStream.
Usage
Example to find the root of f(x) = x + B*x/sqrt(1 + sqr(x)) - A
using Newton-Raphson iteration
\verbatim
A 1;
B 1;
x #stream
#{
// Lookup the coefficients
const scalar A = $A;
const scalar B = $B;
// Initial guess for x
scalar x = 0;
scalar x0 = x;
do
{
// Store the previous iteration x for the convergence check
x0 = x;
// Temporary sub-function evaluations
const scalar f1 = 1 + sqr(x);
const scalar f2 = sqrt(f1);
// Evaluate the function
const scalar f = x + B*x/f2 - A;
// Evaluate the derivative
const scalar df = 1 + B/(f1*f2);
// Update x
x = x0 - f/df;
// Test for convergence
} while (mag(x - x0) > 1e-6);
os << x;
#};
\endverbatim
See also
Foam::functionEntries::codeIncludeEntry
Foam::functionEntries::codeStream
Foam::functionEntries::calc
SourceFiles
streamEntry.C
\*---------------------------------------------------------------------------*/
#ifndef streamEntry_H
#define streamEntry_H
#include "functionEntry.H"
#include "OTstream.H"
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
namespace Foam
{
namespace functionEntries
{
// Forward declaration of friend classes
class codeBlockEntry;
/*---------------------------------------------------------------------------*\
Class streamEntry Declaration
\*---------------------------------------------------------------------------*/
class streamEntry
:
public functionEntry
{
protected:
// Protected Member Functions
//- Return the code string
static string codeString
(
const label index,
const dictionary& codeDict,
Istream&,
const string& startString = string::null,
const string& endString = string::null
);
//- Perform the calculation and return the result in an OTstream
static OTstream resultStream
(
const dictionary& dict,
Istream& is,
const string& startString = string::null,
const string& endString = string::null
);
public:
// Related types
//- Declare friendship with the streamEntry class
friend class codeBlockEntry;
//- Runtime type information
FunctionTypeName("#stream");
// Constructors
//- Construct from line number, dictionary and Istream
streamEntry
(
const label lineNumber,
const dictionary& parentDict,
Istream& is
);
//- Copy construct
streamEntry(const streamEntry&) = default;
//- Clone
virtual autoPtr<entry> clone(const dictionary&) const
{
return autoPtr<entry>(new streamEntry(*this));
}
// Member Functions
//- Expand the functionEntry into the contextDict
virtual bool execute(dictionary& contextDict, Istream&);
//- Expand the functionEntry into the contextEntry
static bool execute
(
const dictionary& contextDict,
primitiveEntry& contextEntry,
Istream&
);
// Member Operators
//- Disallow default bitwise assignment
void operator=(const streamEntry&) = delete;
};
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
} // End namespace functionEntries
} // End namespace Foam
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
#endif
// ************************************************************************* //
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