/// <summary>
/// Force a root found by a non-bracketing solver to lie on a specified side,
/// as if the solver was a bracketing one. </summary>
/// <param name="maxEval"> maximal number of new evaluations of the function
/// (evaluations already done for finding the root should have already been subtracted
/// from this number) </param>
/// <param name="f"> function to solve </param>
/// <param name="bracketing"> bracketing solver to use for shifting the root </param>
/// <param name="baseRoot"> original root found by a previous non-bracketing solver </param>
/// <param name="min"> minimal bound of the search interval </param>
/// <param name="max"> maximal bound of the search interval </param>
/// <param name="allowedSolution"> the kind of solutions that the root-finding algorithm may
/// accept as solutions. </param>
/// <returns> a root approximation, on the specified side of the exact root </returns>
/// <exception cref="NoBracketingException"> if the function has the same sign at the
/// endpoints. </exception>
public static double ForceSide(int maxEval, UnivariateFunction f, BracketedUnivariateSolver <UnivariateFunction> bracketing, double baseRoot, double min, double max, AllowedSolution allowedSolution)
{
if (allowedSolution == AllowedSolution.ANY_SIDE)
{
// no further bracketing required
return(baseRoot);
}
// find a very small interval bracketing the root
double step = FastMath.Max(bracketing.AbsoluteAccuracy, FastMath.Abs(baseRoot * bracketing.RelativeAccuracy));
double xLo = FastMath.Max(min, baseRoot - step);
double fLo = f.Value(xLo);
double xHi = FastMath.Min(max, baseRoot + step);
double fHi = f.Value(xHi);
int remainingEval = maxEval - 2;
while (remainingEval > 0)
{
if ((fLo >= 0 && fHi <= 0) || (fLo <= 0 && fHi >= 0))
{
// compute the root on the selected side
return(bracketing.Solve(remainingEval, f, xLo, xHi, baseRoot, allowedSolution));
}
// try increasing the interval
bool changeLo = false;
bool changeHi = false;
if (fLo < fHi)
{
// increasing function
if (fLo >= 0)
{
changeLo = true;
}
else
{
changeHi = true;
}
}
else if (fLo > fHi)
{
// decreasing function
if (fLo <= 0)
{
changeLo = true;
}
else
{
changeHi = true;
}
}
else
{
// unknown variation
changeLo = true;
changeHi = true;
}
// update the lower bound
if (changeLo)
{
xLo = FastMath.Max(min, xLo - step);
fLo = f.Value(xLo);
remainingEval--;
}
// update the higher bound
if (changeHi)
{
xHi = FastMath.Min(max, xHi + step);
fHi = f.Value(xHi);
remainingEval--;
}
}
throw new NoBracketingException("LocalizedFormats.FAILED_BRACKETING", xLo, xHi, fLo, fHi, maxEval - remainingEval, maxEval, baseRoot, min, max);
}
/// <summary>
/// Force a root found by a non-bracketing solver to lie on a specified side,
/// as if the solver were a bracketing one.
/// </summary>
/// <param name="maxEval"> maximal number of new evaluations of the function
/// (evaluations already done for finding the root should have already been subtracted
/// from this number) </param>
/// <param name="f"> function to solve </param>
/// <param name="bracketing"> bracketing solver to use for shifting the root </param>
/// <param name="baseRoot"> original root found by a previous non-bracketing solver </param>
/// <param name="min"> minimal bound of the search interval </param>
/// <param name="max"> maximal bound of the search interval </param>
/// <param name="allowedSolution"> the kind of solutions that the root-finding algorithm may
/// accept as solutions. </param>
/// <returns> a root approximation, on the specified side of the exact root </returns>
/// <exception cref="NoBracketingException"> if the function has the same sign at the
/// endpoints. </exception>
//JAVA TO C# CONVERTER WARNING: 'final' parameters are not available in .NET:
//ORIGINAL LINE: public static double forceSide(final int maxEval, final org.apache.commons.math3.analysis.UnivariateFunction f, final BracketedUnivariateSolver<org.apache.commons.math3.analysis.UnivariateFunction> bracketing, final double baseRoot, final double min, final double max, final AllowedSolution allowedSolution) throws org.apache.commons.math3.exception.NoBracketingException
public static double ForceSide(int maxEval, UnivariateFunction f, BracketedUnivariateSolver <UnivariateFunction> bracketing, double baseRoot, double min, double max, AllowedSolution allowedSolution)
{
if (allowedSolution == AllowedSolution.ANY_SIDE)
{
// no further bracketing required
return(baseRoot);
}
// find a very small interval bracketing the root
//JAVA TO C# CONVERTER WARNING: The original Java variable was marked 'final':
//ORIGINAL LINE: final double step = org.apache.commons.math3.util.FastMath.max(bracketing.getAbsoluteAccuracy(), org.apache.commons.math3.util.FastMath.abs(baseRoot * bracketing.getRelativeAccuracy()));
double step = FastMath.Max(bracketing.GetAbsoluteAccuracy(), FastMath.Abs(baseRoot * bracketing.GetRelativeAccuracy()));
double xLo = FastMath.Max(min, baseRoot - step);
double fLo = f.Value(xLo);
double xHi = FastMath.Min(max, baseRoot + step);
double fHi = f.Value(xHi);
int remainingEval = maxEval - 2;
while (remainingEval > 0)
{
if ((fLo >= 0 && fHi <= 0) || (fLo <= 0 && fHi >= 0))
{
// compute the root on the selected side
return(bracketing.Solve(remainingEval, f, xLo, xHi, baseRoot, allowedSolution));
}
// try increasing the interval
bool changeLo = false;
bool changeHi = false;
if (fLo < fHi)
{
// increasing function
if (fLo >= 0)
{
changeLo = true;
}
else
{
changeHi = true;
}
}
else if (fLo > fHi)
{
// decreasing function
if (fLo <= 0)
{
changeLo = true;
}
else
{
changeHi = true;
}
}
else
{
// unknown variation
changeLo = true;
changeHi = true;
}
// update the lower bound
if (changeLo)
{
xLo = FastMath.Max(min, xLo - step);
fLo = f.Value(xLo);
remainingEval--;
}
// update the higher bound
if (changeHi)
{
xHi = FastMath.Min(max, xHi + step);
fHi = f.Value(xHi);
remainingEval--;
}
}
throw new NoBracketingException(LocalizedFormats.FAILED_BRACKETING, xLo, xHi, fLo, fHi, maxEval - remainingEval, maxEval, baseRoot, min, max);
}
