void abuswap(double *m, int *nr, int *nc, int *thin, int *direct)
{
int row[2], col[2], k, ij[4], changed, ev ;
double sm[4];
GetRNGstate();
changed = 0;
while (changed < *thin) {
/* Select a random 2x2 matrix*/
i2rand(row, *nr - 1);
i2rand(col, *nc - 1);
ij[0] = INDX(row[0], col[0], *nr);
ij[1] = INDX(row[1], col[0], *nr);
ij[2] = INDX(row[0], col[1], *nr);
ij[3] = INDX(row[1], col[1], *nr);
for (k = 0; k < 4; k ++)
sm[k] = m[ij[k]];
ev = isDiagSimple(sm);
/* Swap */
if (ev == 1) {
/* fixed column sums */
if (*direct == 0) {
m[ij[0]] = sm[1];
m[ij[1]] = sm[0];
m[ij[2]] = sm[3];
m[ij[3]] = sm[2];
}
/* fixed row sums */
else {
m[ij[0]] = sm[2];
m[ij[1]] = sm[3];
m[ij[2]] = sm[0];
m[ij[3]] = sm[1];
}
changed++;
}
}
PutRNGstate();
}
static void abuswap(double *m, int *nr, int *nc, int *thin, int *direct)
{
int k, ij[4], changed, ev;
size_t intcheck;
double sm[4];
/* GetRNGstate in calling C code */
/* GetRNGstate(); */
changed = 0;
intcheck = 0;
while (changed < *thin) {
/* Select a random 2x2 matrix*/
get2x2((*nr) * (*nc) - 1, *nr, ij);
for (k = 0; k < 4; k++)
sm[k] = m[ij[k]];
ev = isDiagSimple(sm);
/* Swap */
if (ev == 1) {
/* fixed column sums */
if (*direct == 0) {
m[ij[0]] = sm[1];
m[ij[1]] = sm[0];
m[ij[2]] = sm[3];
m[ij[3]] = sm[2];
}
/* fixed row sums */
else {
m[ij[0]] = sm[2];
m[ij[1]] = sm[3];
m[ij[2]] = sm[0];
m[ij[3]] = sm[1];
}
changed++;
}
if (intcheck % 10000 == 9999)
R_CheckUserInterrupt();
intcheck++;
}
/* PutRNGstate(); */
}
