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#include <stdio.h>
#include <inttypes.h>
#include <cmath>
#include "triode.h"
using std::abs;
#define DUMP(x) x
T Triode::compute(T a, T R, T Vgate, T Vk) {
T VakGuess = 100.;
T Vgk = Vgate - Vk;
T Vak = VakGuess; // initial guess
int iteration = 0;
T err = 1e6;
T Iak = 0.0;
while (fabs(err)/fabs(Vak) > 1e-9){
VakGuess = iterateNewtonRaphson(Vak, 1e-6, Vgk, a, R);
err = Vak - VakGuess;
Vak = VakGuess;
if (iteration > 100){
printf("Convergence failure!");
break;
}
++iteration;
}
T b = Vak - R*Iak;
//printf("Vgate=%f Vk=%f Vgk=%f b=%f\n", Vgate, Vk, Vgk, b);
return b;
}
T Triode::getIa(T Vgk, T Vak) {
if (Vak < 0.0) {
printf("Less than zero!\n");
Vak = 0.0;
}
if (Vgk > 0.0) {
Vgk = 0.0;
}
T mu = 100.;
T kx = 1.4;
T kg1 = 3.981e-8;
T kp = 600.;
T kvb = 300.;
T e1 = Vak/kp*log(1.+exp(kp*(1./mu+Vgk/pow(kvb+Vak*Vak, 0.5))));
if (e1 < 0) {
return 0.;
}
return (pow(e1, kx) / kg1);
}
T Triode::evaluateImplicitEquation(T Vak, T Vgk, T a, T R){
T Iak = getIa(Vgk, Vak);
return Vak + R*Iak - a;
}
T Triode::iterateNewtonRaphson(T x, T dx, T Vgk, T a, T R){
T F = evaluateImplicitEquation(x, Vgk, a, R);
T xNew = x - dx*F/(evaluateImplicitEquation(x + dx, Vgk, a, R) - F);
return xNew;
}
Triode::Triode()
{
vg = 0.0;
vk = 0.0;
vp = 0.0;
insane = false;
}
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