// Tube Equation Test
// Copyright 2008 Les Hall
// This software is protected by the GNU General Public License


float Vin, Vo, Ia, Vak, Vgk, Vo_prev, Vsum, Verror;
int i;
100 => float Vaa;
100000 => float Ra;
100 => float Rk;
100000 => float Rl;
0.000001 => float K;
100 => float mu;


// do the calculations
Vaa/2 => Vo;
Vo/100 => Vgk;
Vo/2 => Vak;
for (-10 => int j; j < 11; j++) {  // sweep the input voltage
    j / 10.0 => Vin;
    Vo => Verror;
    0 => i;
    while ( (Math.fabs(Verror) > 0.5) & (i < 100) ) {  // iterate over solution
        i++;  // increment iteration counter
        Vo => Vo_prev;  // save previous guess at output
        Vo - Verror => Vo;  // walk output along solution curve
        Vin - Rk*Ia => Vgk;  // calculate tube input voltage
        Vo - Rk*Ia => Vak;  // calculate tube output voltage
        mu * Vgk + Vak => Vsum;  // calculate interior term of Ia
        if (Vsum <= 0) {  // apply zero region
            0 => Vsum;
        }
        K * Math.pow (Vsum, 1.5) => Ia;  // calculate tube output current
        (1 / (1/Ra + 1/Rl)) * (Vaa/Ra - Ia) => Vo;  // calculate output voltage
        Vo - Vo_prev => Verror;  // calculate error voltage
        100::samp => now;
    }
    //<<<i, Vin, Verror, Vgk, Vak, Ia, Vo>>>;
    <<<0.1, (Vaa/2 - Vo) / (Vaa/2)>>>;
}