
/*
 * -- SuperLU routine (version 2.0) --
 * Univ. of California Berkeley, Xerox Palo Alto Research Center,
 * and Lawrence Berkeley National Lab.
 * November 15, 1997
 *
 */
/*
Copyright (c) 2003, The Regents of the University of California, through
Lawrence Berkeley National Laboratory (subject to receipt of any required 
approvals from U.S. Dept. of Energy) 

All rights reserved. 

The source code is distributed under BSD license, see the file License.txt
*/

/*
 * This file defines common arithmetic operations for complex type.
 */
#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#include "slu_dcomplex.h"


/* Complex Division c = a/b */
void z_div(doublecomplex *c, doublecomplex *a, doublecomplex *b)
{
    double ratio, den;
    double abr, abi, cr, ci;
  
    if( (abr = b->r) < 0.)
	abr = - abr;
    if( (abi = b->i) < 0.)
	abi = - abi;
    if( abr <= abi ) {
	if (abi == 0) {
	    fprintf(stderr, "z_div.c: division by zero\n");
            exit(-1);
	}	  
	ratio = b->r / b->i ;
	den = b->i * (1 + ratio*ratio);
	cr = (a->r*ratio + a->i) / den;
	ci = (a->i*ratio - a->r) / den;
    } else {
	ratio = b->i / b->r ;
	den = b->r * (1 + ratio*ratio);
	cr = (a->r + a->i*ratio) / den;
	ci = (a->i - a->r*ratio) / den;
    }
    c->r = cr;
    c->i = ci;
}


/* Returns sqrt(z.r^2 + z.i^2) */
double z_abs(doublecomplex *z)
{
    double temp;
    double real = z->r;
    double imag = z->i;

    if (real < 0) real = -real;
    if (imag < 0) imag = -imag;
    if (imag > real) {
	temp = real;
	real = imag;
	imag = temp;
    }
    if ((real+imag) == real) return(real);
  
    temp = imag/real;
    temp = real*sqrt(1.0 + temp*temp);  /*overflow!!*/
    return (temp);
}


/* Approximates the abs */
/* Returns abs(z.r) + abs(z.i) */
double z_abs1(doublecomplex *z)
{
    double real = z->r;
    double imag = z->i;
  
    if (real < 0) real = -real;
    if (imag < 0) imag = -imag;

    return (real + imag);
}

/* Return the exponentiation */
void z_exp(doublecomplex *r, doublecomplex *z)
{
    double expx;

    expx = exp(z->r);
    r->r = expx * cos(z->i);
    r->i = expx * sin(z->i);
}

/* Return the complex conjugate */
void d_cnjg(doublecomplex *r, doublecomplex *z)
{
    r->r = z->r;
    r->i = -z->i;
}

/* Return the imaginary part */
double d_imag(doublecomplex *z)
{
    return (z->i);
}


