public static double[] ciqf(int nt, double[] t, int[] mlt, int nwts, ref int[] ndx, int key,
int kind, double alpha, double beta, double a, double b, int lo)
//****************************************************************************80
//
// Purpose:
//
// CIQF computes weights for a classical weight function and any interval.
//
// Discussion:
//
// This routine compute somes or all the weights of a quadrature formula
// for a classical weight function with any valid A, B and a given set of
// knots and multiplicities.
//
// The weights may be packed into the output array WTS according to a
// user-defined pattern or sequentially.
//
// The routine will also optionally print knots and weights and a check
// of the moments.
//
// Licensing:
//
// This code is distributed under the GNU LGPL license.
//
// Modified:
//
// 07 January 2010
//
// Author:
//
// Original FORTRAN77 version by Sylvan Elhay, Jaroslav Kautsky.
// C++ version by John Burkardt.
//
// Reference:
//
// Sylvan Elhay, Jaroslav Kautsky,
// Algorithm 655: IQPACK, FORTRAN Subroutines for the Weights of
// Interpolatory Quadrature,
// ACM Transactions on Mathematical Software,
// Volume 13, Number 4, December 1987, pages 399-415.
//
// Parameters:
//
// Input, int NT, the number of knots.
//
// Input, double T[NT], the knots.
//
// Input, int MLT[NT], the multiplicity of the knots.
//
// Input, int NWTS, the number of weights.
//
// Input/output, int NDX[NT], used to index the output
// array WTS. If KEY = 1, then NDX need not be preset. For more
// details see the comments in CAWIQ.
//
// Input, int KEY, indicates the structure of the WTS
// array. It will normally be set to 1. This will cause the weights to be
// packed sequentially in array WTS. For more details see the comments
// in CAWIQ.
//
// Input, int KIND, the rule.
// 1, Legendre, (a,b) 1.0
// 2, Chebyshev Type 1, (a,b) ((b-x)*(x-a))^(-0.5)
// 3, Gegenbauer, (a,b) ((b-x)*(x-a))^alpha
// 4, Jacobi, (a,b) (b-x)^alpha*(x-a)^beta
// 5, Generalized Laguerre, (a,+oo) (x-a)^alpha*exp(-b*(x-a))
// 6, Generalized Hermite, (-oo,+oo) |x-a|^alpha*exp(-b*(x-a)^2)
// 7, Exponential, (a,b) |x-(a+b)/2.0|^alpha
// 8, Rational, (a,+oo) (x-a)^alpha*(x+b)^beta
// 9, Chebyshev Type 2, (a,b) ((b-x)*(x-a))^(+0.5)
//
// Input, double ALPHA, the value of Alpha, if needed.
//
// Input, double BETA, the value of Beta, if needed.
//
// Input, double A, B, the interval endpoints.
//
// Input, int LO, selects the actions to perform.
// > 0, compute and print weights. Print moments check.
// = 0, compute weights.
// < 0, compute and print weights.
//
// Output, double CIQF[NWTS], the weights.
//
{
int j;
int m = 1;
int l = Math.Abs(key);
for (j = 0; j < nt; j++)
{
if (l == 1 || Math.Abs(ndx[j]) != 0)
{
m += mlt[j];
}
}
if (nwts + 1 < m)
{
Console.WriteLine("");
Console.WriteLine("CIQF - Fatal error!");
Console.WriteLine(" NWTS + 1 < M.");
return(null);
}
int mex = 2 + m;
//
// Scale the knots to default A, B.
//
double[] st = SCT.sct(nt, t, kind, a, b);
//
// Compute the weights.
//
const int lu = 0;
double[] wts = CIQFS.ciqfs(nt, st, mlt, nwts, ref ndx, key, kind, alpha, beta, lu);
//
// Don't scale user's knots - only scale weights.
//
SCQF.scqf(nt, st, mlt, wts, nwts, ndx, ref wts, ref st, kind, alpha, beta, a, b);
if (lo == 0)
{
return(wts);
}
int mop = m - 1;
CHKQF.chkqf(t, wts, mlt, nt, nwts, ndx, key, mop, mex, kind,
alpha, beta, lo, a, b);
return(wts);
}
public static void cgqf(int nt, int kind, double alpha, double beta, double a, double b,
int lo, ref double[] t, ref double[] wts)
//****************************************************************************80
//
// Purpose:
//
// CGQF computes knots and weights of a Gauss quadrature formula.
//
// Discussion:
//
// The user may specify the interval (A,B).
//
// Only simple knots are produced.
//
// Use routine EIQFS to evaluate this quadrature formula.
//
// Licensing:
//
// This code is distributed under the GNU LGPL license.
//
// Modified:
//
// 16 February 2010
//
// Author:
//
// Original FORTRAN77 version by Sylvan Elhay, Jaroslav Kautsky.
// C++ version by John Burkardt.
//
// Reference:
//
// Sylvan Elhay, Jaroslav Kautsky,
// Algorithm 655: IQPACK, FORTRAN Subroutines for the Weights of
// Interpolatory Quadrature,
// ACM Transactions on Mathematical Software,
// Volume 13, Number 4, December 1987, pages 399-415.
//
// Parameters:
//
// Input, int NT, the number of knots.
//
// Input, int KIND, the rule.
// 1, Legendre, (a,b) 1.0
// 2, Chebyshev Type 1, (a,b) ((b-x)*(x-a))^-0.5)
// 3, Gegenbauer, (a,b) ((b-x)*(x-a))^alpha
// 4, Jacobi, (a,b) (b-x)^alpha*(x-a)^beta
// 5, Generalized Laguerre, (a,+oo) (x-a)^alpha*exp(-b*(x-a))
// 6, Generalized Hermite, (-oo,+oo) |x-a|^alpha*exp(-b*(x-a)^2)
// 7, Exponential, (a,b) |x-(a+b)/2.0|^alpha
// 8, Rational, (a,+oo) (x-a)^alpha*(x+b)^beta
// 9, Chebyshev Type 2, (a,b) ((b-x)*(x-a))^(+0.5)
//
// Input, double ALPHA, the value of Alpha, if needed.
//
// Input, double BETA, the value of Beta, if needed.
//
// Input, double A, B, the interval endpoints, or
// other parameters.
//
// Input, int LO, defines the actions:
// < 0, compute knots and weights, and print.
// = 0, compute knots and weights.
// > 0, compute knots and weights, print, and do moment check.
//
// Output, double T[NT], the knots.
//
// Output, double WTS[NT], the weights.
//
{
int i;
//
// Check that there is enough workspace and assign it.
//
const int key = 1;
int mop = 2 * nt;
int m = mop + 1;
int mex = m + 2;
int mmex = Math.Max(mex, 1);
//
// Compute the Gauss quadrature formula for default values of A and B.
//
CDGQF.cdgqf(nt, kind, alpha, beta, ref t, ref wts);
//
// Prepare to scale the quadrature formula to other weight function with
// valid A and B.
//
int[] mlt = new int[nt];
for (i = 0; i < nt; i++)
{
mlt[i] = 1;
}
int[] ndx = new int[nt];
for (i = 0; i < nt; i++)
{
ndx[i] = i + 1;
}
SCQF.scqf(nt, t, mlt, wts, nt, ndx, ref wts, ref t, kind, alpha, beta, a, b);
//
// Exit if no print required.
//
if (lo != 0)
{
CHKQF.chkqf(t, wts, mlt, nt, nt, ndx, key, mop, mmex,
kind, alpha, beta, lo, a, b);
}
}
