landosG.c File Reference

Function to use Lanczos method for approximating DOS for the generalized eigenvalue problem. More...

#include <float.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include "blaslapack.h"
#include "def.h"
#include "evsl.h"
#include "internal_proto.h"
#include "string.h"
#include "struct.h"

Go to the source code of this file.

Functions
int	LanDosG (const int nvec, const int msteps, int npts, double *xdos, double *ydos, double *neig, const double *const intv)

Detailed Description

Function to use Lanczos method for approximating DOS for the generalized eigenvalue problem.

Definition in file landosG.c.

Function Documentation

int LanDosG	(	const int	nvec,
		const int	msteps,
		int	npts,
		double *	xdos,
		double *	ydos,
		double *	neig,
		const double *const	intv
	)

---

Computes the density of states (DOS, or spectral density) using Lanczos algorithm for the generalized eigenvalue problem.

Parameters

[in]	nvec	number of sample vectors used
[in]	msteps	number of Lanczos steps
[in]	npts	number of sample points used for the DOS curve
[in]	*intv	Stores the the intervals of interest intv[0:1] = [a b] = interval where DOS is to be computed intv[2:3] = [lambda_min, lambda_max] \
[out]	*xdos	Length-npts long vector, x-coordinate points for plotting the DOS. Must be preallocated before calling LanDos
[out]	*ydos	Length-npts long vector, y-coordinate points for plotting the DOS. Must be preallocated before calling LanDos
[out]	neig	estimated number of eigenvalues

Note

This works for both the standard and generalized eigenvalue problems.

landos.c/LanDos is only for the standard eigenvalue problem.

Definition at line 43 of file landosG.c.

References Calloc, CGS_DGKS(), CGS_DGKS2(), DAXPY(), DCOPY(), DDOT(), DNRM2(), DSCAL(), evsldata, _evsldata::ifGenEv, linspace(), Malloc, max, min, _evsldata::n, NGS_MAX, orthTol, PI, rand_double(), randn_double(), simpson(), and SymmTridEig().

Referenced by main().

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