private static int qzvec(int n, double[][] a, double[][] b, double[] alfr, double[] alfi, double[] beta, double[][] z)
{
int i, j, k, m;
int na, ii, en, jj, nn, enm2;
double d, q;
double r = 0, s = 0, t, w, x = 0, y, t1, t2, w1, x1 = 0, z1 = 0, di;
double ra, dr, sa;
double ti, rr, tr, zz = 0;
double alfm, almi, betm, almr;
double epsb = b[n - 1][0];
int isw = 1;
// for en=n step -1 until 1 do --
for (nn = 0; nn < n; ++nn)
{
en = n - nn - 1;
na = en - 1;
if (isw == 2) goto L795;
if (alfi[en] != 0.0) goto L710;
// Real vector
m = en;
b[en][en] = 1.0;
if (na == -1) goto L800;
alfm = alfr[m];
betm = beta[m];
// for i=en-1 step -1 until 1 do --
for (ii = 0; ii <= na; ++ii)
{
i = en - ii - 1;
w = betm * a[i][i] - alfm * b[i][i];
r = 0.0;
for (j = m; j <= en; ++j)
r += (betm * a[i][j] - alfm * b[i][j]) * b[j][en];
if (i == 0 || isw == 2)
goto L630;
if (betm * a[i][i - 1] == 0.0)
goto L630;
zz = w;
s = r;
goto L690;
L630:
m = i;
if (isw == 2) goto L640;
// Real 1-by-1 block
t = w;
if (w == 0.0)
t = epsb;
b[i][en] = -r / t;
goto L700;
// Real 2-by-2 block
L640:
x = betm * a[i][i + 1] - alfm * b[i][i + 1];
y = betm * a[i + 1][i];
q = w * zz - x * y;
t = (x * s - zz * r) / q;
b[i][en] = t;
if (Math.Abs(x) <= Math.Abs(zz)) goto L650;
b[i + 1][en] = (-r - w * t) / x;
goto L690;
L650:
b[i + 1][en] = (-s - y * t) / zz;
L690:
isw = 3 - isw;
L700:
;
}
// End real vector
goto L800;
// Complex vector
L710:
m = na;
almr = alfr[m];
almi = alfi[m];
betm = beta[m];
// last vector component chosen imaginary so that eigenvector matrix is triangular
y = betm * a[en][na];
b[na][na] = -almi * b[en][en] / y;
b[na][en] = (almr * b[en][en] - betm * a[en][en]) / y;
b[en][na] = 0.0;
b[en][en] = 1.0;
enm2 = na;
if (enm2 == 0) goto L795;
// for i=en-2 step -1 until 1 do --
for (ii = 0; ii < enm2; ++ii)
{
i = na - ii - 1;
w = betm * a[i][i] - almr * b[i][i];
w1 = -almi * b[i][i];
ra = 0.0;
sa = 0.0;
for (j = m; j <= en; ++j)
{
x = betm * a[i][j] - almr * b[i][j];
x1 = -almi * b[i][j];
ra = ra + x * b[j][na] - x1 * b[j][en];
sa = sa + x * b[j][en] + x1 * b[j][na];
}
if (i == 0 || isw == 2) goto L770;
if (betm * a[i][i - 1] == 0.0) goto L770;
zz = w;
z1 = w1;
r = ra;
s = sa;
isw = 2;
goto L790;
L770:
m = i;
if (isw == 2) goto L780;
// Complex 1-by-1 block
tr = -ra;
ti = -sa;
L773:
dr = w;
di = w1;
// Complex divide (t1,t2) = (tr,ti) / (dr,di)
L775:
if (Math.Abs(di) > Math.Abs(dr)) goto L777;
rr = di / dr;
d = dr + di * rr;
t1 = (tr + ti * rr) / d;
t2 = (ti - tr * rr) / d;
switch (isw)
{
case 1: goto L787;
case 2: goto L782;
}
L777:
rr = dr / di;
d = dr * rr + di;
t1 = (tr * rr + ti) / d;
t2 = (ti * rr - tr) / d;
switch (isw)
{
case 1: goto L787;
case 2: goto L782;
}
// Complex 2-by-2 block
L780:
x = betm * a[i][i + 1] - almr * b[i][i + 1];
x1 = -almi * b[i][i + 1];
y = betm * a[i + 1][i];
tr = y * ra - w * r + w1 * s;
ti = y * sa - w * s - w1 * r;
dr = w * zz - w1 * z1 - x * y;
di = w * z1 + w1 * zz - x1 * y;
if (dr == 0.0 && di == 0.0)
dr = epsb;
goto L775;
L782:
b[i + 1][na] = t1;
b[i + 1][en] = t2;
isw = 1;
if (Math.Abs(y) > Math.Abs(w) + Math.Abs(w1))
goto L785;
tr = -ra - x * b[(i + 1)][na] + x1 * b[(i + 1)][en];
ti = -sa - x * b[(i + 1)][en] - x1 * b[(i + 1)][na];
goto L773;
L785:
t1 = (-r - zz * b[(i + 1)][na] + z1 * b[(i + 1)][en]) / y;
t2 = (-s - zz * b[(i + 1)][en] - z1 * b[(i + 1)][na]) / y;
L787:
b[i][na] = t1;
b[i][en] = t2;
L790:
;
}
// End complex vector
L795:
isw = 3 - isw;
L800:
;
}
// End back substitution. Transform to original coordinate system.
for (jj = 0; jj < n; ++jj)
{
j = n - jj - 1;
for (i = 0; i < n; ++i)
{
zz = 0.0;
for (k = 0; k <= j; ++k)
zz += z[i][k] * b[k][j];
z[i][j] = zz;
}
}
// Normalize so that modulus of largest component of each vector is 1.
// (isw is 1 initially from before)
for (j = 0; j < n; ++j)
{
d = 0.0;
if (isw == 2) goto L920;
if (alfi[j] != 0.0) goto L945;
for (i = 0; i < n; ++i)
{
if ((Math.Abs(z[i][j])) > d)
d = (Math.Abs(z[i][j]));
}
for (i = 0; i < n; ++i)
z[i][j] /= d;
goto L950;
L920:
for (i = 0; i < n; ++i)
{
r = System.Math.Abs(z[i][j - 1]) + System.Math.Abs(z[i][j]);
if (r != 0.0)
{
// Computing 2nd power
double u1 = z[i][j - 1] / r;
double u2 = z[i][j] / r;
r *= Math.Sqrt(u1 * u1 + u2 * u2);
}
if (r > d)
d = r;
}
for (i = 0; i < n; ++i)
{
z[i][j - 1] /= d;
z[i][j] /= d;
}
L945:
isw = 3 - isw;
L950:
;
}
return 0;
}
