/*
   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).
 * ALGEBRAIC[0] is Istim in component stimulus_protocol (per_ms).
 * CONSTANTS[0] is IstimStart in component stimulus_protocol (ms).
 * CONSTANTS[1] is IstimEnd in component stimulus_protocol (ms).
 * CONSTANTS[2] is IstimAmplitude in component stimulus_protocol (per_ms).
 * CONSTANTS[3] is IstimPeriod in component stimulus_protocol (ms).
 * CONSTANTS[4] is IstimPulseDuration in component stimulus_protocol (ms).
 * STATES[0] is u in component membrane (dimensionless).
 * CONSTANTS[5] is Cm in component membrane (uF_per_cm2).
 * ALGEBRAIC[1] is Vm in component membrane (mV).
 * CONSTANTS[6] is V_0 in component membrane (mV).
 * CONSTANTS[7] is V_fi in component membrane (mV).
 * ALGEBRAIC[4] is J_fi in component fast_inward_current (per_ms).
 * ALGEBRAIC[6] is J_so in component slow_outward_current (per_ms).
 * ALGEBRAIC[7] is J_si in component slow_inward_current (per_ms).
 * ALGEBRAIC[2] is p in component p (dimensionless).
 * CONSTANTS[8] is u_c in component p (dimensionless).
 * ALGEBRAIC[3] is q in component q (dimensionless).
 * CONSTANTS[9] is u_v in component q (dimensionless).
 * CONSTANTS[21] is tau_d in component fast_inward_current (ms).
 * CONSTANTS[10] 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[5] is tau_v_minus in component fast_inward_current_v_gate (ms).
 * CONSTANTS[11] is tau_v1_minus in component fast_inward_current_v_gate (ms).
 * CONSTANTS[12] is tau_v2_minus in component fast_inward_current_v_gate (ms).
 * CONSTANTS[13] is tau_v_plus in component fast_inward_current_v_gate (ms).
 * CONSTANTS[14] is tau_0 in component slow_outward_current (ms).
 * CONSTANTS[15] is tau_r in component slow_outward_current (ms).
 * CONSTANTS[16] is tau_si in component slow_inward_current (ms).
 * CONSTANTS[17] is u_csi in component slow_inward_current (dimensionless).
 * CONSTANTS[18] is k in component slow_inward_current (dimensionless).
 * STATES[2] is w in component slow_inward_current_w_gate (dimensionless).
 * CONSTANTS[19] is tau_w_minus in component slow_inward_current_w_gate (ms).
 * CONSTANTS[20] is tau_w_plus in component slow_inward_current_w_gate (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)
{
CONSTANTS[0] = 100;
CONSTANTS[1] = 50000;
CONSTANTS[2] = -0.2;
CONSTANTS[3] = 1000;
CONSTANTS[4] = 1;
STATES[0] = 0;
CONSTANTS[5] = 1;
CONSTANTS[6] = -85;
CONSTANTS[7] = 15;
CONSTANTS[8] = 0.13;
CONSTANTS[9] = 0;
CONSTANTS[10] = 5.8;
STATES[1] = 1;
CONSTANTS[11] = 18.2;
CONSTANTS[12] = 18.2;
CONSTANTS[13] = 10;
CONSTANTS[14] = 12.5;
CONSTANTS[15] = 130;
CONSTANTS[16] = 127;
CONSTANTS[17] = 0.85;
CONSTANTS[18] = 10;
STATES[2] = 1;
CONSTANTS[19] = 80;
CONSTANTS[20] = 1020;
CONSTANTS[21] = CONSTANTS[5]/CONSTANTS[10];
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[4]+ALGEBRAIC[6]+ALGEBRAIC[7]+ALGEBRAIC[0]);
resid[1] = RATES[1] - ( (1.00000 - ALGEBRAIC[2])*(1.00000 - STATES[1]))/ALGEBRAIC[5] - ( ALGEBRAIC[2]*STATES[1])/CONSTANTS[13];
resid[2] = RATES[2] - ( (1.00000 - ALGEBRAIC[2])*(1.00000 - STATES[2]))/CONSTANTS[19] - ( ALGEBRAIC[2]*STATES[2])/CONSTANTS[20];
}
void
computeVariables(double VOI, double* CONSTANTS, double* RATES, double* STATES, double* ALGEBRAIC)
{
ALGEBRAIC[1] = CONSTANTS[6]+ STATES[0]*(CONSTANTS[7] - CONSTANTS[6]);
}
void
computeEssentialVariables(double VOI, double* CONSTANTS, double* RATES, double* STATES, double* ALGEBRAIC)
{
ALGEBRAIC[0] = (CONDVAR[0]>=0.00000&&CONDVAR[1]<=0.00000&&CONDVAR[2]<=0.00000 ? CONSTANTS[2] : 0.00000);
ALGEBRAIC[2] = (CONDVAR[3]<0.00000 ? 0.00000 : 1.00000);
ALGEBRAIC[4] = ( - STATES[1]*ALGEBRAIC[2]*(1.00000 - STATES[0])*(STATES[0] - CONSTANTS[8]))/CONSTANTS[21];
ALGEBRAIC[3] = (CONDVAR[4]<0.00000 ? 0.00000 : 1.00000);
ALGEBRAIC[5] =  ALGEBRAIC[3]*CONSTANTS[11]+ (1.00000 - ALGEBRAIC[3])*CONSTANTS[12];
ALGEBRAIC[6] = ( STATES[0]*(1.00000 - ALGEBRAIC[2]))/CONSTANTS[14]+ALGEBRAIC[2]/CONSTANTS[15];
ALGEBRAIC[7] = ( - STATES[2]*(1.00000+ tanh( CONSTANTS[18]*(STATES[0] - CONSTANTS[17]))))/( 2.00000*CONSTANTS[16]);
}
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] = VOI - CONSTANTS[0];
CONDVAR[1] = VOI - CONSTANTS[1];
CONDVAR[2] = ((VOI - CONSTANTS[0]) -  floor((VOI - CONSTANTS[0])/CONSTANTS[3])*CONSTANTS[3]) - CONSTANTS[4];
CONDVAR[3] = STATES[0] - CONSTANTS[8];
CONDVAR[4] = STATES[0] - CONSTANTS[9];
}