/*
**
** DGEFA benchmark
**
** We would like to declare a[][lda], but c does not allow it. In this
** function, references to a[i][j] are written a[lda*i+j].
**
** dgefa factors a double precision matrix by gaussian elimination.
**
** dgefa is usually called by dgeco, but it can be called
** directly with a saving in time if rcond is not needed.
** (time for dgeco) = (1 + 9/n)*(time for dgefa) .
**
** on entry
**
** a REAL precision[n][lda]
** the matrix to be factored.
**
** lda integer
** the leading dimension of the array a .
**
** n integer
** the order of the matrix a .
**
** on return
**
** a an upper triangular matrix and the multipliers
** which were used to obtain it.
** the factorization can be written a = l*u where
** l is a product of permutation and unit lower
** triangular matrices and u is upper triangular.
**
** ipvt integer[n]
** an integer vector of pivot indices.
**
** info integer
** = 0 normal value.
** = k if u[k][k] .eq. 0.0 . this is not an error
** condition for this subroutine, but it does
** indicate that dgesl or dgedi will divide by zero
** if called. use rcond in dgeco for a reliable
** indication of singularity.
**
** linpack. this version dated 08/14/78 .
** cleve moler, university of New Mexico, argonne national lab.
**
** functions
**
** blas daxpy,dscal,idamax
**
*/
static void dgefa(REAL *a,int lda,int n,int *ipvt,int *info,int roll)
{
REAL t;
int /*idamax(),*/j,k,kp1,l,nm1;
/* gaussian elimination with partial pivoting */
if (roll)
{
*info = 0;
nm1 = n - 1;
if (nm1 >= 0)
for (k = 0; k < nm1; k++)
{
kp1 = k + 1;
/* find l = pivot index */
l = idamax(n-k,&a[lda*k+k],1) + k;
ipvt[k] = l;
/* zero pivot implies this column already
triangularized */
if (a[lda*k+l] != ZERO)
{
/* interchange if necessary */
if (l != k)
{
t = a[lda*k+l];
a[lda*k+l] = a[lda*k+k];
a[lda*k+k] = t;
}
/* compute multipliers */
t = -ONE/a[lda*k+k];
dscal_r(n-(k+1),t,&a[lda*k+k+1],1);
/* row elimination with column indexing */
for (j = kp1; j < n; j++)
{
t = a[lda*j+l];
if (l != k)
{
a[lda*j+l] = a[lda*j+k];
a[lda*j+k] = t;
}
daxpy_r(n-(k+1),t,&a[lda*k+k+1],1,&a[lda*j+k+1],1);
}
}
else
(*info) = k;
}
ipvt[n-1] = n-1;
if (a[lda*(n-1)+(n-1)] == ZERO)
(*info) = n-1;
}
else
{
*info = 0;
nm1 = n - 1;
if (nm1 >= 0)
for (k = 0; k < nm1; k++)
{
kp1 = k + 1;
/* find l = pivot index */
l = idamax(n-k,&a[lda*k+k],1) + k;
ipvt[k] = l;
/* zero pivot implies this column already
triangularized */
if (a[lda*k+l] != ZERO)
{
/* interchange if necessary */
if (l != k)
{
t = a[lda*k+l];
a[lda*k+l] = a[lda*k+k];
a[lda*k+k] = t;
}
/* compute multipliers */
t = -ONE/a[lda*k+k];
dscal_ur(n-(k+1),t,&a[lda*k+k+1],1);
/* row elimination with column indexing */
for (j = kp1; j < n; j++)
{
t = a[lda*j+l];
if (l != k)
{
a[lda*j+l] = a[lda*j+k];
a[lda*j+k] = t;
}
daxpy_ur(n-(k+1),t,&a[lda*k+k+1],1,&a[lda*j+k+1],1);
}
}
else
(*info) = k;
}
ipvt[n-1] = n-1;
if (a[lda*(n-1)+(n-1)] == ZERO)
(*info) = n-1;
}
}
void dgefa(int *a,int lda,int n,int *ipvt,int *info,int roll)
{
int t;
int idamax(),j,k,kp1,l,nm1;
if (roll>=1)
{
*info = 0;
nm1 = n - 1;
if (nm1 >= 0)
for (k = 0; k < nm1; k++)
{
kp1 = k + 1;
l = idamax(n-k,&a[lda*k+k],1) + k;
ipvt[k] = l;
if (!(a[lda*k+l] == ZERO))
{
if (!(l == k))
{
t = a[lda*k+l];
a[lda*k+l] = a[lda*k+k];
a[lda*k+k] = t;
}
t = -ONE/a[lda*k+k];
dscal_r(n-(k+1),t,&a[lda*k+k+1],1);
for (j = kp1; j < n; j++)
{
t = a[lda*j+l];
if (!(l == k))
{
a[lda*j+l] = a[lda*j+k];
a[lda*j+k] = t;
}
daxpy_r(n-(k+1),t,&a[lda*k+k+1],1,&a[lda*j+k+1],1);
}
}
else
(*info) = k;
}
ipvt[n-1] = n-1;
if (a[lda*(n-1)+(n-1)] == ZERO)
(*info) = n-1;
}
else
{
*info = 0;
nm1 = n - 1;
if (nm1 >= 0)
for (k = 0; k < nm1; k++)
{
kp1 = k + 1;
l = idamax(n-k,&a[lda*k+k],1) + k;
ipvt[k] = l;
if (!(a[lda*k+l] == ZERO))
{
if (!(l == k))
{
t = a[lda*k+l];
a[lda*k+l] = a[lda*k+k];
a[lda*k+k] = t;
}
t = -ONE/a[lda*k+k];
dscal_ur(n-(k+1),t,&a[lda*k+k+1],1);
for (j = kp1; j < n; j++)
{
t = a[lda*j+l];
if (!(l == k))
{
a[lda*j+l] = a[lda*j+k];
a[lda*j+k] = t;
}
daxpy_ur(n-(k+1),t,&a[lda*k+k+1],1,&a[lda*j+k+1],1);
}
}
else
(*info) = k;
}
ipvt[n-1] = n-1;
if (a[lda*(n-1)+(n-1)] == ZERO)
(*info) = n-1;
}
}