Category : Miscellaneous Language Source Code
Archive   : LINPACK.ZIP
Filename : LINPACKD.F

double precision aa(200,200),a(201,200),b(200),x(200)
double precision time(8,6),cray,ops,total,norma,normx
double precision resid,residn,eps,epslon
integer*4 t1,second
integer ipvt(200)
lda = 201
ldaa = 200
c
n = 100
cray = .056
write(6,1)
1 format(' Please send the results of this run to:'//
$ ' Jack J. Dongarra'/
$ ' Mathematics and Computer Science Division'/
$ ' Argonne National Laboratory'/
$ ' Argonne, Illinois 60439'//
$ ' Telephone: 312-972-7246'//
$ ' ARPAnet: DONGARRA@ANL-MCS'/)
ops = (2.0d0*n**3)/3.0d0 + 2.0d0*n**2
c
call matgen(a,lda,n,b,norma)
t1 = second()
call dgefa(a,lda,n,ipvt,info)
time(1,1) = second() - t1
t1 = second()
call dgesl(a,lda,n,ipvt,b,0)
time(1,2) = second() - t1
total = time(1,1) + time(1,2)
c
c compute a residual to verify results.
c
do 10 i = 1,n
x(i) = b(i)
10 continue
call matgen(a,lda,n,b,norma)
do 20 i = 1,n
b(i) = -b(i)
20 continue
call dmxpy(n,b,n,lda,x,a)
resid = 0.0
normx = 0.0
do 30 i = 1,n
resid = dmax1( resid, dabs(b(i)) )
normx = dmax1( normx, dabs(x(i)) )
30 continue
eps = epslon(1.0d0)
residn = resid/( n*norma*normx*eps )
write(6,40)
40 format(' norm. resid resid machep',
$ ' x(1) x(n)')
write(6,50) residn,resid,eps,x(1),x(n)
50 format(1p5e16.8)
c
write(6,60) n
60 format(//' times are reported for matrices of order ',i5)
write(6,70)
70 format(6x,'dgefa',6x,'dgesl',6x,'total',5x,'mflops',7x,'unit',
$ 6x,'ratio')
c
time(1,3) = total
time(1,4) = ops/(1.0d6*total)
time(1,5) = 2.0d0/time(1,4)
time(1,6) = total/cray
write(6,80) lda
80 format(' times for array with leading dimension of',i4)
write(6,110) (time(1,i),i=1,6)
c
call matgen(a,lda,n,b,norma)
t1 = second()
call dgefa(a,lda,n,ipvt,info)
time(2,1) = second() - t1
t1 = second()
call dgesl(a,lda,n,ipvt,b,0)
time(2,2) = second() - t1
total = time(2,1) + time(2,2)
time(2,3) = total
time(2,4) = ops/(1.0d6*total)
time(2,5) = 2.0d0/time(2,4)
time(2,6) = total/cray
c
call matgen(a,lda,n,b,norma)
t1 = second()
call dgefa(a,lda,n,ipvt,info)
time(3,1) = second() - t1
t1 = second()
call dgesl(a,lda,n,ipvt,b,0)
time(3,2) = second() - t1
total = time(3,1) + time(3,2)
time(3,3) = total
time(3,4) = ops/(1.0d6*total)
time(3,5) = 2.0d0/time(3,4)
time(3,6) = total/cray
c
ntimes = 10
tm2 = 0
t1 = second()
do 90 i = 1,ntimes
tm = second()
call matgen(a,lda,n,b,norma)
tm2 = tm2 + second() - tm
call dgefa(a,lda,n,ipvt,info)
90 continue
time(4,1) = (second() - t1 - tm2)/ntimes
t1 = second()
do 100 i = 1,ntimes
call dgesl(a,lda,n,ipvt,b,0)
100 continue
time(4,2) = (second() - t1)/ntimes
total = time(4,1) + time(4,2)
time(4,3) = total
time(4,4) = ops/(1.0d6*total)
time(4,5) = 2.0d0/time(4,4)
time(4,6) = total/cray
c
write(6,110) (time(2,i),i=1,6)
write(6,110) (time(3,i),i=1,6)
write(6,110) (time(4,i),i=1,6)
110 format(6(1pe11.3))
c
call matgen(aa,ldaa,n,b,norma)
t1 = second()
call dgefa(aa,ldaa,n,ipvt,info)
time(5,1) = second() - t1
t1 = second()
call dgesl(aa,ldaa,n,ipvt,b,0)
time(5,2) = second() - t1

total = time(5,1) + time(5,2)
time(5,3) = total
time(5,4) = ops/(1.0d6*total)
time(5,5) = 2.0d0/time(5,4)
time(5,6) = total/cray
c
call matgen(aa,ldaa,n,b,norma)
t1 = second()
call dgefa(aa,ldaa,n,ipvt,info)
time(6,1) = second() - t1
t1 = second()
call dgesl(aa,ldaa,n,ipvt,b,0)
time(6,2) = second() - t1
total = time(6,1) + time(6,2)
time(6,3) = total
time(6,4) = ops/(1.0d6*total)
time(6,5) = 2.0d0/time(6,4)
time(6,6) = total/cray
c
call matgen(aa,ldaa,n,b,norma)
t1 = second()
call dgefa(aa,ldaa,n,ipvt,info)
time(7,1) = second() - t1
t1 = second()
call dgesl(aa,ldaa,n,ipvt,b,0)
time(7,2) = second() - t1
total = time(7,1) + time(7,2)
time(7,3) = total
time(7,4) = ops/(1.0d6*total)
time(7,5) = 2.0d0/time(7,4)
time(7,6) = total/cray
c
ntimes = 10
tm2 = 0
t1 = second()
do 120 i = 1,ntimes
tm = second()
call matgen(aa,ldaa,n,b,norma)
tm2 = tm2 + second() - tm
call dgefa(aa,ldaa,n,ipvt,info)
120 continue
time(8,1) = (second() - t1 - tm2)/ntimes
t1 = second()
do 130 i = 1,ntimes
call dgesl(aa,ldaa,n,ipvt,b,0)
130 continue
time(8,2) = (second() - t1)/ntimes
total = time(8,1) + time(8,2)
time(8,3) = total
time(8,4) = ops/(1.0d6*total)
time(8,5) = 2.0d0/time(8,4)
time(8,6) = total/cray
c
write(6,140) ldaa
140 format(/' times for array with leading dimension of',i4)
write(6,110) (time(5,i),i=1,6)
write(6,110) (time(6,i),i=1,6)
write(6,110) (time(7,i),i=1,6)
write(6,110) (time(8,i),i=1,6)

ravg = 0.0
do 145 i = 1,8
145 ravg = time(i,4) + ravg
ravg = ravg / 8.0
write (6,150) ravg
150 format ("The average mflops is ",1pe11.3)
stop
end
subroutine matgen(a,lda,n,b,norma)
double precision a(lda,1),b(1),norma
c
init = 1325
norma = 0.0
do 30 j = 1,n
do 20 i = 1,n
init = mod(3125*init,65536)
a(i,j) = (init - 32768.0)/16384.0
norma = dmax1(dabs(a(i,j)), norma)
20 continue
30 continue
do 35 i = 1,n
b(i) = 0.0
35 continue
do 50 j = 1,n
do 40 i = 1,n
b(i) = b(i) + a(i,j)
40 continue
50 continue
return
end
subroutine dgefa(a,lda,n,ipvt,info)
integer lda,n,ipvt(1),info
double precision a(lda,1)
c
c dgefa factors a double precision matrix by gaussian elimination.
c
c dgefa is usually called by dgeco, but it can be called
c directly with a saving in time if rcond is not needed.
c (time for dgeco) = (1 + 9/n)*(time for dgefa) .
c
c on entry
c
c a double precision(lda, n)
c the matrix to be factored.
c
c lda integer
c the leading dimension of the array a .
c
c n integer
c the order of the matrix a .
c
c on return
c
c a an upper triangular matrix and the multipliers
c which were used to obtain it.
c the factorization can be written a = l*u where
c l is a product of permutation and unit lower
c triangular matrices and u is upper triangular.
c
c ipvt integer(n)
c an integer vector of pivot indices.
c
c info integer
c = 0 normal value.
c = k if u(k,k) .eq. 0.0 . this is not an error
c condition for this subroutine, but it does
c indicate that dgesl or dgedi will divide by zero
c if called. use rcond in dgeco for a reliable
c indication of singularity.
c
c linpack. this version dated 08/14/78 .
c cleve moler, university of new mexico, argonne national lab.
c
c subroutines and functions
c
c blas daxpy,dscal,idamax
c
c internal variables
c
double precision t
integer idamax,j,k,kp1,l,nm1
c
c
c gaussian elimination with partial pivoting
c
info = 0
nm1 = n - 1
if (nm1 .lt. 1) go to 70
do 60 k = 1, nm1
kp1 = k + 1
c
c find l = pivot index
c
l = idamax(n-k+1,a(k,k),1) + k - 1
ipvt(k) = l
c
c zero pivot implies this column already triangularized
c
if (a(l,k) .eq. 0.0d0) go to 40
c
c interchange if necessary
c
if (l .eq. k) go to 10
t = a(l,k)
a(l,k) = a(k,k)
a(k,k) = t
10 continue
c
c compute multipliers
c
t = -1.0d0/a(k,k)
call dscal(n-k,t,a(k+1,k),1)
c
c row elimination with column indexing
c
do 30 j = kp1, n
t = a(l,j)
if (l .eq. k) go to 20
a(l,j) = a(k,j)
a(k,j) = t
20 continue
call daxpy(n-k,t,a(k+1,k),1,a(k+1,j),1)
30 continue
go to 50
40 continue
info = k
50 continue
60 continue
70 continue
ipvt(n) = n
if (a(n,n) .eq. 0.0d0) info = n
return
end
subroutine dgesl(a,lda,n,ipvt,b,job)
integer lda,n,ipvt(1),job
double precision a(lda,1),b(1)
c
c dgesl solves the double precision system
c a * x = b or trans(a) * x = b
c using the factors computed by dgeco or dgefa.
c
c on entry
c
c a double precision(lda, n)
c the output from dgeco or dgefa.
c
c lda integer
c the leading dimension of the array a .
c
c n integer
c the order of the matrix a .
c
c ipvt integer(n)
c the pivot vector from dgeco or dgefa.
c
c b double precision(n)
c the right hand side vector.
c
c job integer
c = 0 to solve a*x = b ,
c = nonzero to solve trans(a)*x = b where
c trans(a) is the transpose.
c
c on return
c
c b the solution vector x .
c
c error condition
c
c a division by zero will occur if the input factor contains a
c zero on the diagonal. technically this indicates singularity
c but it is often caused by improper arguments or improper
c setting of lda . it will not occur if the subroutines are
c called correctly and if dgeco has set rcond .gt. 0.0
c or dgefa has set info .eq. 0 .
c
c to compute inverse(a) * c where c is a matrix
c with p columns
c call dgeco(a,lda,n,ipvt,rcond,z)
c if (rcond is too small) go to ...
c do 10 j = 1, p
c call dgesl(a,lda,n,ipvt,c(1,j),0)
c 10 continue
c
c linpack. this version dated 08/14/78 .
c cleve moler, university of new mexico, argonne national lab.
c
c subroutines and functions
c
c blas daxpy,ddot
c
c internal variables
c
double precision ddot,t
integer k,kb,l,nm1
c
nm1 = n - 1
if (job .ne. 0) go to 50
c
c job = 0 , solve a * x = b
c first solve l*y = b
c
if (nm1 .lt. 1) go to 30
do 20 k = 1, nm1
l = ipvt(k)
t = b(l)
if (l .eq. k) go to 10
b(l) = b(k)
b(k) = t
10 continue
call daxpy(n-k,t,a(k+1,k),1,b(k+1),1)
20 continue
30 continue
c
c now solve u*x = y
c
do 40 kb = 1, n
k = n + 1 - kb
b(k) = b(k)/a(k,k)
t = -b(k)
call daxpy(k-1,t,a(1,k),1,b(1),1)
40 continue
go to 100
50 continue
c
c job = nonzero, solve trans(a) * x = b
c first solve trans(u)*y = b
c
do 60 k = 1, n
t = ddot(k-1,a(1,k),1,b(1),1)
b(k) = (b(k) - t)/a(k,k)
60 continue
c
c now solve trans(l)*x = y
c
if (nm1 .lt. 1) go to 90
do 80 kb = 1, nm1
k = n - kb
b(k) = b(k) + ddot(n-k,a(k+1,k),1,b(k+1),1)
l = ipvt(k)
if (l .eq. k) go to 70
t = b(l)
b(l) = b(k)
b(k) = t
70 continue
80 continue
90 continue
100 continue
return
end
subroutine daxpy(n,da,dx,incx,dy,incy)
c
c constant times a vector plus a vector.
c jack dongarra, linpack, 3/11/78.
c
double precision dx(1),dy(1),da
integer i,incx,incy,ix,iy,m,mp1,n
c
if(n.le.0)return
if (da .eq. 0.0d0) return
if(incx.eq.1.and.incy.eq.1)go to 20

c
c code for unequal increments or equal increments
c not equal to 1
c
ix = 1
iy = 1
if(incx.lt.0)ix = (-n+1)*incx + 1
if(incy.lt.0)iy = (-n+1)*incy + 1
do 10 i = 1,n
dy(iy) = dy(iy) + da*dx(ix)
ix = ix + incx
iy = iy + incy
10 continue
return
c
c code for both increments equal to 1
c
20 continue
do 30 i = 1,n
dy(i) = dy(i) + da*dx(i)
30 continue
return
end
double precision function ddot(n,dx,incx,dy,incy)
c
c forms the dot product of two vectors.
c jack dongarra, linpack, 3/11/78.
c
double precision dx(1),dy(1),dtemp
integer i,incx,incy,ix,iy,m,mp1,n
c
ddot = 0.0d0
dtemp = 0.0d0
if(n.le.0)return
if(incx.eq.1.and.incy.eq.1)go to 20
c
c code for unequal increments or equal increments
c not equal to 1
c
ix = 1
iy = 1
if(incx.lt.0)ix = (-n+1)*incx + 1
if(incy.lt.0)iy = (-n+1)*incy + 1
do 10 i = 1,n
dtemp = dtemp + dx(ix)*dy(iy)
ix = ix + incx
iy = iy + incy
10 continue
ddot = dtemp
return
c
c code for both increments equal to 1
c
20 continue
do 30 i = 1,n
dtemp = dtemp + dx(i)*dy(i)
30 continue
ddot = dtemp
return
end
subroutine dscal(n,da,dx,incx)
c
c scales a vector by a constant.
c jack dongarra, linpack, 3/11/78.
c
double precision da,dx(1)
integer i,incx,m,mp1,n,nincx
c
if(n.le.0)return
if(incx.eq.1)go to 20
c
c code for increment not equal to 1
c
nincx = n*incx
do 10 i = 1,nincx,incx
dx(i) = da*dx(i)
10 continue
return
c
c code for increment equal to 1
c
20 continue
do 30 i = 1,n
dx(i) = da*dx(i)
30 continue
return
end
integer function idamax(n,dx,incx)
c
c finds the index of element having max. dabsolute value.
c jack dongarra, linpack, 3/11/78.
c
double precision dx(1),dmax
integer i,incx,ix,n
c
idamax = 0
if( n .lt. 1 ) return
idamax = 1
if(n.eq.1)return
if(incx.eq.1)go to 20
c
c code for increment not equal to 1
c
ix = 1
dmax = dabs(dx(1))
ix = ix + incx
do 10 i = 2,n
if(dabs(dx(ix)).le.dmax) go to 5
idamax = i
dmax = dabs(dx(ix))
5 ix = ix + incx
10 continue
return
c
c code for increment equal to 1
c
20 dmax = dabs(dx(1))
do 30 i = 2,n
if(dabs(dx(i)).le.dmax) go to 30
idamax = i
dmax = dabs(dx(i))
30 continue
return
end
double precision function epslon (x)
double precision x
c
c estimate unit roundoff in quantities of size x.
c
double precision a,b,c,eps
c
c this program should function properly on all systems
c satisfying the following two assumptions,
c 1. the base used in representing dfloating point
c numbers is not a power of three.
c 2. the quantity a in statement 10 is represented to
c the accuracy used in dfloating point variables
c that are stored in memory.
c the statement number 10 and the go to 10 are intended to
c force optimizing compilers to generate code satisfying
c assumption 2.
c under these assumptions, it should be true that,
c a is not exactly equal to four-thirds,
c b has a zero for its last bit or digit,
c c is not exactly equal to one,
c eps measures the separation of 1.0 from
c the next larger dfloating point number.
c the developers of eispack would appreciate being informed
c about any systems where these assumptions do not hold.
c
c *****************************************************************
c this routine is one of the auxiliary routines used by eispack iii
c to avoid machine dependencies.
c *****************************************************************
c
c this version dated 4/6/83.
c
a = 4.0d0/3.0d0
10 b = a - 1.0d0
c = b + b + b
eps = dabs(c-1.0d0)
if (eps .eq. 0.0d0) go to 10
epslon = eps*dabs(x)
return
end
subroutine dmxpy (n1, y, n2, ldm, x, m)
double precision y(*), x(*), m(ldm,*)
c
c purpose:
c multiply matrix m times vector x and add the result to vector y.
c
c parameters:
c
c n1 integer, number of elements in vector y, and number of rows in
c matrix m
c
c y double precision(n1), vector of length n1 to which is added
c the product m*x
c
c n2 integer, number of elements in vector x, and number of columns
c in matrix m
c
c ldm integer, leading dimension of array m
c
c x double precision(n2), vector of length n2
c
c m double precision(ldm,n2), matrix of n1 rows and n2 columns
c
c ----------------------------------------------------------------------
c
c cleanup odd vector
c
j = mod(n2,2)
if (j .ge. 1) then
do 10 i = 1, n1
y(i) = (y(i)) + x(j)*m(i,j)
10 continue
endif
c
c cleanup odd group of two vectors
c
j = mod(n2,4)
if (j .ge. 2) then
do 20 i = 1, n1
y(i) = ( (y(i))
$ + x(j-1)*m(i,j-1)) + x(j)*m(i,j)
20 continue
endif
c
c cleanup odd group of four vectors
c
j = mod(n2,8)
if (j .ge. 4) then
do 30 i = 1, n1
y(i) = ((( (y(i))
$ + x(j-3)*m(i,j-3)) + x(j-2)*m(i,j-2))
$ + x(j-1)*m(i,j-1)) + x(j) *m(i,j)
30 continue
endif
c
c cleanup odd group of eight vectors
c
j = mod(n2,16)
if (j .ge. 8) then
do 40 i = 1, n1
y(i) = ((((((( (y(i))
$ + x(j-7)*m(i,j-7)) + x(j-6)*m(i,j-6))
$ + x(j-5)*m(i,j-5)) + x(j-4)*m(i,j-4))
$ + x(j-3)*m(i,j-3)) + x(j-2)*m(i,j-2))
$ + x(j-1)*m(i,j-1)) + x(j) *m(i,j)
40 continue
endif
c
c main loop - groups of sixteen vectors
c
jmin = j+16
do 60 j = jmin, n2, 16
do 50 i = 1, n1
y(i) = ((((((((((((((( (y(i))
$ + x(j-15)*m(i,j-15)) + x(j-14)*m(i,j-14))
$ + x(j-13)*m(i,j-13)) + x(j-12)*m(i,j-12))
$ + x(j-11)*m(i,j-11)) + x(j-10)*m(i,j-10))
$ + x(j- 9)*m(i,j- 9)) + x(j- 8)*m(i,j- 8))
$ + x(j- 7)*m(i,j- 7)) + x(j- 6)*m(i,j- 6))
$ + x(j- 5)*m(i,j- 5)) + x(j- 4)*m(i,j- 4))
$ + x(j- 3)*m(i,j- 3)) + x(j- 2)*m(i,j- 2))
$ + x(j- 1)*m(i,j- 1)) + x(j) *m(i,j)
50 continue
60 continue
return
end