landos.c File Reference

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

#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	LanDos (const int nvec, 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 standard eigenvalue problem.

Definition in file landos.c.

Function Documentation

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

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Computes the density of states (DOS, or spectral density)

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 two 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 only works with the standard eigenvalue problem. Use landosG.c /LanDosG for the generalized eigenvalue problem.

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Definition at line 40 of file landos.c.

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

Referenced by main().

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