/*
   There are a total of 8 entries in the algebraic variable array.
   There are a total of 3 entries in each of the rate and state variable arrays.
   There are a total of 22 entries in the constant variable array.
 */
/*
 * VOI is time in component environment (ms).
 * STATES[0] is u in component membrane (dimensionless).
 * CONSTANTS[0] is Cm in component membrane (uF_per_cm2).
 * ALGEBRAIC[0] is Vm in component membrane (mV).
 * CONSTANTS[1] is V_0 in component membrane (mV).
 * CONSTANTS[2] is V_fi in component membrane (mV).
 * ALGEBRAIC[3] is J_fi in component fast_inward_current (per_ms).
 * ALGEBRAIC[5] is J_so in component slow_outward_current (per_ms).
 * ALGEBRAIC[6] is J_si in component slow_inward_current (per_ms).
 * ALGEBRAIC[7] is Istim in component stimulus_protocol (per_ms).
 * ALGEBRAIC[1] is p in component p (dimensionless).
 * CONSTANTS[3] is u_c in component p (dimensionless).
 * ALGEBRAIC[2] is q in component q (dimensionless).
 * CONSTANTS[4] is u_v in component q (dimensionless).
 * CONSTANTS[21] is tau_d in component fast_inward_current (ms).
 * CONSTANTS[5] is g_fi_max in component fast_inward_current (mS_per_cm2).
 * STATES[1] is v in component fast_inward_current_v_gate (dimensionless).
 * ALGEBRAIC[4] is tau_v_minus in component fast_inward_current_v_gate (ms).
 * CONSTANTS[6] is tau_v1_minus in component fast_inward_current_v_gate (ms).
 * CONSTANTS[7] is tau_v2_minus in component fast_inward_current_v_gate (ms).
 * CONSTANTS[8] is tau_v_plus in component fast_inward_current_v_gate (ms).
 * CONSTANTS[9] is tau_0 in component slow_outward_current (ms).
 * CONSTANTS[10] is tau_r in component slow_outward_current (ms).
 * CONSTANTS[11] is tau_si in component slow_inward_current (ms).
 * CONSTANTS[12] is u_csi in component slow_inward_current (dimensionless).
 * CONSTANTS[13] is k in component slow_inward_current (dimensionless).
 * STATES[2] is w in component slow_inward_current_w_gate (dimensionless).
 * CONSTANTS[14] is tau_w_minus in component slow_inward_current_w_gate (ms).
 * CONSTANTS[15] is tau_w_plus in component slow_inward_current_w_gate (ms).
 * CONSTANTS[16] is IstimStart in component stimulus_protocol (ms).
 * CONSTANTS[17] is IstimEnd in component stimulus_protocol (ms).
 * CONSTANTS[18] is IstimAmplitude in component stimulus_protocol (per_ms).
 * CONSTANTS[19] is IstimPeriod in component stimulus_protocol (ms).
 * CONSTANTS[20] is IstimPulseDuration in component stimulus_protocol (ms).
 * RATES[0] is d/dt u in component membrane (dimensionless).
 * RATES[1] is d/dt v in component fast_inward_current_v_gate (dimensionless).
 * RATES[2] is d/dt w in component slow_inward_current_w_gate (dimensionless).
 * There are a total of 5 condition variables.
 */
void
initConsts(double* CONSTANTS, double* RATES, double *STATES)
{
STATES[0] = 0;
CONSTANTS[0] = 1;
CONSTANTS[1] = -85;
CONSTANTS[2] = 15;
CONSTANTS[3] = 0.13;
CONSTANTS[4] = 0.04;
CONSTANTS[5] = 4;
STATES[1] = 1;
CONSTANTS[6] = 1250;
CONSTANTS[7] = 19.6;
CONSTANTS[8] = 3.33;
CONSTANTS[9] = 12.5;
CONSTANTS[10] = 33.33;
CONSTANTS[11] = 29;
CONSTANTS[12] = 0.85;
CONSTANTS[13] = 10;
STATES[2] = 1;
CONSTANTS[14] = 41;
CONSTANTS[15] = 870;
CONSTANTS[16] = 10;
CONSTANTS[17] = 50000;
CONSTANTS[18] = -0.2;
CONSTANTS[19] = 1000;
CONSTANTS[20] = 1;
CONSTANTS[21] = CONSTANTS[0]/CONSTANTS[5];
RATES[0] = 0.1001;
RATES[1] = 0.1001;
RATES[2] = 0.1001;
}
void
computeResiduals(double VOI, double* CONSTANTS, double* RATES, double* OLDRATES, double* STATES,
                 double* OLDSTATES, double* ALGEBRAIC, double* CONDVARS)
{
resid[0] = RATES[0] - - (ALGEBRAIC[3]+ALGEBRAIC[5]+ALGEBRAIC[6]+ALGEBRAIC[7]);
resid[1] = RATES[1] - ( (1.00000 - ALGEBRAIC[1])*(1.00000 - STATES[1]))/ALGEBRAIC[4] - ( ALGEBRAIC[1]*STATES[1])/CONSTANTS[8];
resid[2] = RATES[2] - ( (1.00000 - ALGEBRAIC[1])*(1.00000 - STATES[2]))/CONSTANTS[14] - ( ALGEBRAIC[1]*STATES[2])/CONSTANTS[15];
}
void
computeVariables(double VOI, double* CONSTANTS, double* RATES, double* STATES, double* ALGEBRAIC)
{
ALGEBRAIC[0] = CONSTANTS[1]+ STATES[0]*(CONSTANTS[2] - CONSTANTS[1]);
}
void
computeEssentialVariables(double VOI, double* CONSTANTS, double* RATES, double* STATES, double* ALGEBRAIC)
{
ALGEBRAIC[1] = (CONDVAR[0]<0.00000 ? 0.00000 : 1.00000);
ALGEBRAIC[3] = ( - STATES[1]*ALGEBRAIC[1]*(1.00000 - STATES[0])*(STATES[0] - CONSTANTS[3]))/CONSTANTS[21];
ALGEBRAIC[2] = (CONDVAR[1]<0.00000 ? 0.00000 : 1.00000);
ALGEBRAIC[4] =  ALGEBRAIC[2]*CONSTANTS[6]+ (1.00000 - ALGEBRAIC[2])*CONSTANTS[7];
ALGEBRAIC[5] = ( STATES[0]*(1.00000 - ALGEBRAIC[1]))/CONSTANTS[9]+ALGEBRAIC[1]/CONSTANTS[10];
ALGEBRAIC[6] = ( - STATES[2]*(1.00000+ tanh( CONSTANTS[13]*(STATES[0] - CONSTANTS[12]))))/( 2.00000*CONSTANTS[11]);
ALGEBRAIC[7] = (CONDVAR[2]>=0.00000&&CONDVAR[3]<=0.00000&&CONDVAR[4]<=0.00000 ? CONSTANTS[18] : 0.00000);
}
void
getStateInformation(double* SI)
{
SI[0] = 1.0;
SI[1] = 1.0;
SI[2] = 1.0;
}
void
computeRoots(double VOI, double* CONSTANTS, double* RATES, double* OLDRATES, double* STATES,
             double* OLDSTATES, double* ALGEBRAIC, double* CONDVARS)
{
CONDVAR[0] = STATES[0] - CONSTANTS[3];
CONDVAR[1] = STATES[0] - CONSTANTS[4];
CONDVAR[2] = VOI - CONSTANTS[16];
CONDVAR[3] = VOI - CONSTANTS[17];
CONDVAR[4] = ((VOI - CONSTANTS[16]) -  floor((VOI - CONSTANTS[16])/CONSTANTS[19])*CONSTANTS[19]) - CONSTANTS[20];
}