/*

freesteam - IAPWS-IF97 steam tables library

Copyright (C) 2004-2009 John Pye

This program is free software; you can redistribute it and/or

modify it under the terms of the GNU General Public License

as published by the Free Software Foundation; either version 2

of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

GNU General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program; if not, write to the Free Software

Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

*/

#ifdef __cplusplus

extern "C" {

#endif

#define FREESTEAM_BUILDING_LIB

#include "steam_pu.h"

#include "region1.h"

#include "region2.h"

#include "region3.h"

#include "region4.h"

#include "b23.h"

#include "backwards.h"

#include "zeroin.h"

#include "solver2.h"

#include "common.h"

#include <stdio.h>

#include <stdlib.h>

int freesteam_region_pu(double p, double u){

double p13 = freesteam_region4_psat_T(REGION1_TMAX);

if(p < p13){

double Tsat = freesteam_region4_Tsat_p(p);

double uf = freesteam_region1_u_pT(p,Tsat);

if(u < uf)return 1;

double ug = freesteam_region2_u_pT(p,Tsat);

if(u > ug)return 2;

return 4;

}

double u13 = freesteam_region1_u_pT(p,REGION1_TMAX);

if(u < u13){

return 1;

}

double T23 = freesteam_b23_T_p(p);

double u23 = freesteam_region2_u_pT(p,T23);

if(u > u23){

return 2;

}

if(p > IAPWS97_PCRIT)return 3;

/* FIXME what we really need here is a psat(u) function! The current method

is singular. */

double Tsat = freesteam_region4_Tsat_p(p);

double rhof = freesteam_region4_rhof_T(Tsat);

double uf = freesteam_region3_u_rhoT(rhof,Tsat);

if(u<uf) return 3;

double rhog = freesteam_region4_rhog_T(Tsat);

double ug = freesteam_region3_u_rhoT(rhog,Tsat);

if(u>ug)return 3;

return 4;

}

typedef struct{

double p, u, T;

} SolvePUData;

#define D ((SolvePUData *)user_data)

static ZeroInSubjectFunction pu_region1_fn, pu_region2_fn, pu_region4_fn;

double pu_region1_fn(double T, void *user_data){

return D->u - freesteam_region1_u_pT(D->p, T);

}

double pu_region2_fn(double T, void *user_data){

return D->u - freesteam_region2_u_pT(D->p, T);

}

double pu_region4_fn(double x, void *user_data){

return D->u - freesteam_region4_u_Tx(D->T, x);

}

#undef D

SteamState freesteam_set_pu(double p, double u){

double lb, ub, tol, sol, err;

SolvePUData D = {p, u, 0.};

SteamState S;

int region = freesteam_region_pu(p,u);

switch(region){

case 1:

lb = IAPWS97_TMIN;

ub = REGION1_TMAX;

tol = 1e-9; /* ??? */

zeroin_solve(&pu_region1_fn, &D, lb, ub, tol, &sol, &err);

S = freesteam_region1_set_pT(p,sol);

break;

case 2:

lb = IAPWS97_TMIN;

ub = REGION2_TMAX;

tol = 1e-9; /* ??? */

zeroin_solve(&pu_region2_fn, &D, lb, ub, tol, &sol, &err);

S = freesteam_region2_set_pT(p,sol);

break;

case 4:

lb = 0.;

ub = 1.;

tol = 1e-9; /* ??? */

D.T = freesteam_region4_Tsat_p(p);

//fprintf(stderr,"%s: (%s:%d): p = %g\n",__func__,__FILE__,__LINE__,D.p);

zeroin_solve(&pu_region4_fn, &D, lb, ub, tol, &sol, &err);

S = freesteam_region4_set_Tx(D.T,sol);

break;

case 3:

/* FIXME looks like a problem with the derivative routines here? */

{

int status;

SteamState guess = freesteam_region3_set_rhoT(IAPWS97_RHOCRIT,IAPWS97_TCRIT);

S = freesteam_solver2_region3('p','u', p, u, guess, &status);

if(status){

fprintf(stderr,"%s (%s:%d): Failed solve in region 3 for (p = %g MPa, u = %g kJ/kg\n"

,__func__,__FILE__,__LINE__,p/1e6,u/1e3);

//exit(1);

}

}

break;

default:

fprintf(stderr,"%s (%s:%d): Region '%d' not implemented\n",__func__,__FILE__,__LINE__,region);

exit(1);

}

return S;

}

#ifdef __cplusplus

}

#endif