// Hydrogen

#include "Hydrogen.h"
#include <math.h>

namespace tpx {

static const double
    M = 2.0159,
    Tmn = 13.8,
    Tmx = 5000.0,
    Tc = 32.938,
    Pc = 1.2838e6,
    Roc= 31.36,
    To = 13.8,
    Tt = 13.8,
    Pt = 7042.09,
    R =  4124.299539,
    Gamma = 1.008854772e-3,
    u0 = 308901.4703,
    s0 = 7759.186436,
    T1 = 35,
    T2 = 400,
    alpha = 1.5814454428,     //to be used with psat
    alpha1 = .3479;           //to be used with ldens

static const double Ahydro[] =
	{  1.150470519352900e1, 1.055427998826072e3, -1.270685949968568e4,
	7.287844527295619e4, -7.448780703363973e5, 2.328994151810363e-1,
	-1.635308393739296e1, 3.730678064960389e3, 6.299667723184813e5,
	1.210920358305697e-3, 1.753651095884817, -1.367022988058101e2,
	-6.869936641299885e-3, 3.644494201750974e-2, -2.559784772600182,
	-4.038855202905836e-4, 1.485396303520942e-6, 4.243613981060742e-4,
	-2.307910113586888e-6, -6.082192173879582e5, -1.961080967486886e6,
	-5.786932854076408e2, 2.799129504191752e4, -2.381566558300913e-1,
	8.918796032452872e-1, -6.985739539036644e-5, -7.339554179182899e-3,
	-5.597033440289980e-9, 8.842130160884514e-8, -2.655507264539047e-12,
	-4.544474518140164e-12, 9.818775257001922e-11 };
static const double Dhydro[]=
	{  4.8645813003e1, -3.4779278180e1, 4.0776538192e2,
		-1.1719787304e3, 1.6213924400e3, -1.1531096683e3, 3.3825492039e2  };
static const double Fhydro[]=
	{ 3.05300134164, 2.80810925813, -6.55461216567e-1, 1.59514439374 };
static const double Ghydro[]=
	{ 6.1934792e3, 2.9490437e2, -1.5401979e3, -4.9176101e3, 
	  6.8957165e4, -2.2282185e5, 3.7990059e5, -3.7094216e5, 2.1326792e5,
	  -7.1519411e4, 1.2971743e4, -9.8533014e2, 1.0434776e4,
	  -3.9144179e2, 5.8277696e2, 6.5409163e2, -1.8728847e2  };

double hydrogen::C(int i, double rt, double rt2) {
   switch(i) {
   case 0 : 
      return Ahydro[0] * T + Ahydro[1] * sqrt(T) + Ahydro[2] + (Ahydro[3] + Ahydro[4] * rt) * rt;
   case 1 : 
      return Ahydro[5] * T + Ahydro[6] + rt * (Ahydro[7] + Ahydro[8] * rt);
   case 2 :
      return Ahydro[9] * T + Ahydro[10] + Ahydro[11] * rt; 
   case 3 :
      return Ahydro[12];
   case 4 :
      return rt*(Ahydro[13] + Ahydro[14]*rt);
   case 5 :
      return Ahydro[15]*rt;
   case 6 : 
      return rt*(Ahydro[16] + Ahydro[17]*rt);
   case 7 : 
      return Ahydro[18]*rt2;
   case 8 : 
      return rt2*(Ahydro[19] + Ahydro[20]*rt);
   case 9 : 
      return rt2*(Ahydro[21] + Ahydro[22]*rt2);
   case 10 : 
      return rt2*(Ahydro[23] + Ahydro[24]*rt);
   case 11 : 
      return rt2*(Ahydro[25] + Ahydro[26]*rt2);
   case 12 : 
      return rt2*(Ahydro[27] + Ahydro[28]*rt);
   case 13 : 
      return rt2*(Ahydro[29] + Ahydro[30]*rt + Ahydro[31]*rt2);
   default :
	  return 0.0;
      }
   }

double hydrogen::Cprime(int i, double rt, double rt2, double rt3) {
   switch(i) {
   case 0 : 
      return Ahydro[0] + 0.5*Ahydro[1]/sqrt(T) - (Ahydro[3] + 2.0*Ahydro[4]*rt)*rt2; 
   case 1 : 
      return Ahydro[5] - rt2*(Ahydro[7] + 2.0*Ahydro[8]*rt); 
   case 2 :
      return Ahydro[9] - Ahydro[11]*rt2; 
   case 3 :
      return 0.0;
   case 4 :
      return -rt2*(Ahydro[13] + 2.0*Ahydro[14]*rt);
   case 5 :
      return -Ahydro[15]*rt2;
   case 6 : 
      return -rt2*(Ahydro[16] + 2.0*Ahydro[17]*rt);
   case 7 : 
      return -2.0*Ahydro[18]*rt3; 
   case 8 : 
      return -rt3*(2.0*Ahydro[19] + 3.0*Ahydro[20]*rt);
   case 9 : 
      return -rt3*(2.0*Ahydro[21] + 4.0*Ahydro[22]*rt2);
   case 10 : 
      return -rt3*(2.0*Ahydro[23] + 3.0*Ahydro[24]*rt);
   case 11 : 
      return -rt3*(2.0*Ahydro[25] + 4.0*Ahydro[26]*rt2);
   case 12 : 
      return -rt3*(2.0*Ahydro[27] + 3.0*Ahydro[28]*rt);
   case 13 : 
      return -rt3*(2.0*Ahydro[29] + 3.0*Ahydro[30]*rt + 4.0*Ahydro[31]*rt2);
   default :
	  return 0.0;
      }
   } 

double hydrogen::W(int n, double egrho) {
   return (n == 0 ? (1.0 - egrho)/(2.0*Gamma) : 
	   (n*W(n-1, egrho) - 0.5*pow(Rho,2*n)*egrho)/Gamma);
   }

double hydrogen::H(int i, double egrho) {
   return (i < 8 ? pow(Rho,i+2) : pow(Rho,2*i-13)*egrho); 
   }

double hydrogen::I(int i, double egrho) {
   return (i < 8 ? pow(Rho,i+1)/double(i+1) : W(i-8, egrho)); 
   }

double hydrogen::icv(int i, double x, double xlg) {
   return (i == 0 ? x - 1 : x*pow(xlg,i) - i*icv(i-1,x,xlg));
   }

double hydrogen::up(){
   double rt = 1.0/T;
   double rt2 = rt*rt;
   double rt3 = rt*rt2;
   double egrho = exp(-Gamma*Rho*Rho);
   double x, xlg;   
   double sum = u0;
   double sum2, sum3;
   for (int i=0; i<14; i++)
      sum += (C(i, rt, rt2) - T*Cprime(i, rt, rt2, rt3))*I(i, egrho);

//   add \int c_{v,0} term

   if (T <= T1) { 
      sum2 = Ghydro[0]*T;
   }
   else {
	  if (T < T2) 
		  x = T/T1;
	  else
		  x = T2/T1;
      xlg = log(x);
	  int i;
      for (i=0, sum2=0.0; i<12; i++) 
         sum2 += Ghydro[i]*icv(i, x, xlg);
      sum2 *= T1;
	  sum2 += Ghydro[0]*T1;
      if (T > T2) {
         x = T/T2;
         xlg = log(x);
         for (i=0, sum3=0.0; i<5; i++) 
            sum3 += Ghydro[i+12]*icv(i, x, xlg);
         sum3 *= T2;
		 sum2 += sum3;
	  }
   }
   sum += sum2 + m_energy_offset;
   return sum;
   }

double hydrogen::sp() {
   double rt = 1.0/T;
   double rt2 = rt*rt;
   double rt3 = rt*rt2;
   double egrho = exp(-Gamma*Rho*Rho);
   double x, xlg;
   double sum = s0 - R*log(Rho);
   double sum2, sum3;
   for (int i=0; i<14; i++)
      sum -= Cprime(i, rt, rt2, rt3)*I(i, egrho);

//   add \int c_{v,0}/T term

   if (T <= T1) 
      sum2 = Ghydro[0]*log(T);
   else {
	  if (T < T2)
		  x = T/T1;
	  else
		  x = T2/T1;
      xlg = log(x);
	  int i;
      for (i=0, sum2 = 0.0; i<12; i++) 
		  sum2 += Ghydro[i]*pow(xlg, i+1)/(i+1);
	  sum2 += Ghydro[0]*log(T1);
      if (T > T2) {
		  x = T/T2;
		  xlg = log(x);
		  for (i=0, sum3=0.0; i<5; i++) 
			  sum3 += Ghydro[i+12]*pow(xlg,i+1)/(i+1);
		  sum2 += sum3;
	  }
   }	
   sum += sum2 + m_entropy_offset;
   return sum;
   }

double hydrogen::Pp(){
   double rt = 1.0/T;
   double rt2 = rt*rt;
   //   double rt3 = rt*rt2;
   double egrho = exp(-Gamma*Rho*Rho);

   double P = Rho*R*T;
   for(int i=0; i<14; i++)
      P += C(i, rt, rt2)*H(i, egrho);
   return P;
   }

//equation D4
double hydrogen::ldens(){
if ((T < Tmn) || (T > Tc)) set_Err(TempError); 
double x=1-T/Tc;
double sum, term;
int i;
for(i=1, sum=0; i<=6; i++)
    sum+=Dhydro[i]*pow(x, 1+double(i-1)/3.0);
term = sum+Roc+Dhydro[0]*pow(x,alpha1);
return term;
}


//equation s3
double hydrogen::Psat(){
double x = (1.0 - Tt/T)/(1.0 - Tt/Tc);
double result;
if ((T < Tmn) || (T > Tc)) set_Err(TempError); 
result = Fhydro[0]*x + Fhydro[1]*x*x + Fhydro[2]*x*x*x + 
         Fhydro[3]*x*pow(1-x, alpha);
return exp(result)*Pt;
}

 double hydrogen::Tcrit() {return Tc;}
 double hydrogen::Pcrit() {return Pc;}
 double hydrogen::Vcrit() {return 1.0/Roc;}
 double hydrogen::Tmin() {return Tmn;}
 double hydrogen::Tmax() {return Tmx;}
 char * hydrogen::name() {
   return (char *) m_name.c_str();
 }
 char * hydrogen::formula() {
   return (char *) m_formula.c_str();
 }
 double hydrogen::MolWt() {return M;}

}