More (Static) Linear Components

typedef struct { 
    int n1, n2, ni;             // VSrc has an internal node
    float *V;
} VSrc;   
// dependent sources
typedef struct { 
    int n1, n2;
    int np, nn, ni;   
    float A;         // gain    
} Vcvs;
typedef struct { 
    int n1, n2;
    int np, nn;
    float A; 
} Vccs;

void add_vsrc(int n1,int n2, int ni, float V) {
    // ni for an internal node for an extra row in the equation.
    Component *c = &comps[ncomps++];
    c->type      = STA_T;
    c->stamp     = vsrc_stamp;
    c->u.vsrc    = (VSrc){n1,n2, ni, V};
}
void add_vcvs(int n1, int n2, int np, int nn, int ni, float A) {
    Component *c = &comps[ncomps++];
    c->type      = STA_T;
    c->stamp     = vcvs_stamp;
    c->u.vcvs    = (Vcvs){n1,n2, np,nn, ni, A};
}
void add_vccs(int n1, int n2, int np, int nn, float A) {
    Component *c = &comps[ncomps++];
    c->type      = STA_T;
    c->stamp     = vccs_stamp;
    c->update    = NULL;
    c->u.vccs    = (Vccs){n1,n2, np,nn, A};
}

/* add an ideal voltage source; stamps a "virtual" node (ni) to the circuit.*/
void vsrc_stamp(Component *c, float Gm[][MAT_SIZE], float I[]) {
    VSrc *s = &c->u.vsrc;
    float E = vsrc.V;

    int n1 = s->n1, n2 = s->n2, ni = s->ni;

    // internal node
    if (n1 != -1) {         
        Gm[n1][ni] += 1.0f;
        Gm[ni][n1] += 1.0f;  // symmetry for the voltage equation
    }
    if (n2 != -1) {
        Gm[n2][ni] -= 1.0f;
        Gm[ni][n2] -= 1.0f;
    }

    // Voltage equation: v(n1) - v(n2) = E
    // stamped as  +1·v(n1) -1*v(n2) +0*I_vs  = E
    I[ni] += E;
}

/*
 * Voltage‐Controlled Voltage Source (VCVS):
 *    v(n1)-v(n2) = mu * (v(np)-v(nn))
 * adds one extra current‐unknown at index ni.
 */
void vcvs_stamp(Component *c, float Gm[][MAT_SIZE], float I[]) {
    (void)I;
    Vcvs *s = &c->u.vcvs;
    int n1   = s->n1,
        n2   = s->n2,
        np   = s->np,
        nn   = s->nn,
        ni   = s->ni;
    float mu = s->A;

    if (n1) Gm[n1][ni] +=  1.0f;
    if (n2) Gm[n2][ni] += -1.0f;

    if (n1) Gm[ni][n1] +=  1.0f;
    if (n2) Gm[ni][n2] += -1.0f;
    if (np) Gm[ni][np] += -mu;
    if (nn) Gm[ni][nn] +=  mu;

    //no direct RHS contribution for a pure dependent source
}

/*
 * Voltage‐Controlled Current Source (VCCS):
 *    i = gm * (v(np)-v(nn))
 * injects from n2 to n1.
 */
void vccs_stamp(Component *c, float Gm[][MAT_SIZE], float I[]) {
    (void)I;
    Vccs *s = &c->u.vccs;
    int   n1 = s->n1,
          n2 = s->n2,
          np = s->np,
          nn = s->nn;
    float gm = s->A;

    if (n1 && np) Gm[n1][np] += -gm;
    if (n1 && nn) Gm[n1][nn] += gm;
    if (n2 && np) Gm[n2][np] += gm;
    if (n2 && nn) Gm[n2][nn] += -gm;
}