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arpack-ng/DOCUMENTS/ex-sym.doc
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2011-10-23 22:13:59 +02:00

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c-----------------------------------------------------------------------
c
c\Example-1
c ... Suppose want to solve A*x = lambda*x in regular mode
c ... so OP = A and B = I.
c ... Assume "call matvecA(n,x,y)" computes y = A*x
c ... Assume exact shifts are used
c ...
c ido = 0
c iparam(7) = 1
c
c %------------------------------------%
c | Beginning of reverse communication |
c %------------------------------------%
c 10 continue
c call _saupd ( ido, 'I', n, which, nev, tol, resid, ncv, v, ldv, iparam,
c & ipntr, workd, workl, lworkl, info )
c if (ido .eq. -1 .or. ido .eq. 1) then
c call matvecA (n, workd(ipntr(1)), workd(ipntr(2)))
c go to 10
c end if
c %------------------------------%
c | End of Reverse communication |
c %------------------------------%
c
c ... Call _seupd to postprocess
c ... want the Ritz vectors set rvec = .true. else rvec = .false.
c call _seupd ( rvec, 'All', select, d, z, ldz, sigma, bmat,
c & n, which, nev, tol, resid, ncv, v, ldv, iparam,
c & ipntr, workd, workl, lworkl, info )
c
c stop
c end
c
c\Example-2
c ... Suppose want to solve A*x = lambda*x in shift-invert mode
c ... so OP = inv[A - sigma*I] and B = I.
c ... Assume "call solve(n,rhs,x)" solves [A - sigma*I]*x = rhs
c ... Assume exact shifts are used
c ...
c ido = 0
c iparam(7) = 3
c
c %------------------------------------%
c | Beginning of reverse communication |
c %------------------------------------%
c 10 continue
c call _saupd ( ido, 'I', n, which, nev, tol, resid, ncv, v, ldv, iparam,
c & ipntr, workd, workl, lworkl, info )
c if (ido .eq. -1 .or. ido .eq. 1) then
c call solve (n, workd(ipntr(1)), workd(ipntr(2)))
c go to 10
c end if
c %------------------------------%
c | End of Reverse communication |
c %------------------------------%
c
c ... Call _seupd to postprocess
c ... want the Ritz vectors set rvec = .true. else rvec = .false.
c call _seupd ( rvec, 'All', select, d, z, ldz, sigma, bmat,
c & n, which, nev, tol, resid, ncv, v, ldv, iparam,
c & ipntr, workd, workl, lworkl, info )
c
c\Example-3
c ... Suppose want to solve A*x = lambda*M*x in regular mode
c ... so OP = inv[M]*A and B = M.
c ... Assume "call matvecM(n,x,y)" computes y = M*x
c ... Assume "call matvecA(n,x,y)" computes y = A*x
c ... Assume "call solveM(n,rhs,x)" solves M*x = rhs
c ... Assume user will supplied shifts
c ...
c ido = 0
c iparam(7) = 2
c
c %------------------------------------%
c | Beginning of reverse communication |
c %------------------------------------%
c 10 continue
c call _saupd ( ido, 'G', n, which, nev, tol, resid, ncv, v, ldv, iparam,
c & ipntr, workd, workl, lworkl, info )
c if (ido .eq. -1 .or. ido .eq. 1) then
c call matvecA (n, workd(ipntr(1)), temp_array)
c call _scopy (n, temp_array, 1, workd(ipntr(1)), 1)
c call solveM (n, temp_array, workd(ipntr(2)))
c go to 10
c else if (ido .eq. 2) then
c call matvecM (n, workd(ipntr(1)), workd(ipntr(2)))
c go to 10
c
c ... delete this last conditional if want to use exact shifts
c else if (ido .eq. 3) then
c ... compute shifts and put in the first np locations of work
c np = iparam(8)
c call _copy (np, shifts, 1, workl(ipntr(11), 1)
c go to 10
c end if
c %------------------------------%
c | End of Reverse communication |
c %------------------------------%
c
c ... call _seupd to postprocess
c ... want the Ritz vectors set rvec = .true. else rvec = .false.
c call _seupd ( rvec, 'All', select, d, z, ldz, sigma, bmat,
c & n, which, nev, tol, resid, ncv, v, ldv, iparam,
c & ipntr, workd, workl, lworkl, info )
c stop
c end
c
c\Example-4
c ... Suppose want to solve A*x = lambda*M*x in shift-invert mode
c ... so OP = (inv[A - sigma*M])*M and B = M.
c ... Assume "call matvecM(n,x,y)" computes y = M*x
c ... Assume "call solve(n,rhs,x)" solves [A - sigma*M]*x = rhs
c ... Assume exact shifts are used
c ...
c ido = 0
c iparam(7) = 3
c
c %------------------------------------%
c | Beginning of reverse communication |
c %------------------------------------%
c 10 continue
c call _saupd ( ido, 'G', n, which, nev, tol, resid, ncv, v, ldv, iparam,
c & ipntr, workd, workl, lworkl, info )
c if (ido .eq. -1) then
c call matvecM (n, workd(ipntr(1)), temp_array)
c call solve (n, temp_array, workd(ipntr(2)))
c go to 10
c else if (ido .eq. 1) then
c call solve (n, workd(ipntr(3)), workd(ipntr(2)))
c go to 10
c else if (ido .eq. 2) then
c call matvecM (n, workd(ipntr(1)), workd(ipntr(2)))
c go to 10
c end if
c %------------------------------%
c | End of Reverse communication |
c %------------------------------%
c
c ... call _seupd to postprocess
c ... want the Ritz vectors set rvec = .true. else rvec = .false.
c call _seupd ( rvec, 'All', select, d, z, ldz, sigma, bmat,
c & n, which, nev, tol, resid, ncv, v, ldv, iparam,
c & ipntr, workd, workl, lworkl, info )
c
c stop
c end
c
c\Example-5
c ... Suppose want to solve K*x = lambda*KG*x in Buckling mode
c ... so OP = (inv[K - sigma*KG])*K and B = K.
c ... Assume "call matvecM(n,x,y)" computes y = KG*x
c ... Assume "call matvecA(n,x,y)" computes y = K*x
c ... Assume "call solve(n,rhs,x)" solves [K - sigma*KG]*x = rhs
c ... Assume exact shifts are used
c
c ido = 0
c iparam(7) = 4
c
c %------------------------------------%
c | Beginning of reverse communication |
c %------------------------------------%
c 10 continue
c call _saupd ( ido, 'G', n, which, nev, tol, resid, ncv, v, ldv, iparam,
c & ipntr, workd, workl, lworkl, info )
c if (ido .eq. -1) then
c call matvecA (n, workd(ipntr(1)), temp_array)
c solve (n, temp_array, workd(ipntr(2)))
c go to 10
c else if (ido .eq. 1) then
c call solve (n, workd(ipntr(3)), workd(ipntr(2)))
c go to 10
c else if (ido .eq. 2) then
c call matvecA (n, workd(ipntr(1)), workd(ipntr(2)))
c go to 10
c end if
c %------------------------------%
c | End of Reverse communication |
c %------------------------------%
c
c ... call _seupd to postprocess
c ... want the Ritz vectors set rvec = .true. else rvec = .false.
c call _seupd ( rvec, 'All', select, d, z, ldz, sigma, bmat,
c & n, which, nev, tol, resid, ncv, v, ldv, iparam,
c & ipntr, workd, workl, lworkl, info )
c stop
c end
c
c\Example-6
c ... Suppose want to solve A*x = lambda*M*x in Cayley mode
c ... so OP = inv[A - sigma*M]*[A + sigma*M] and B = M.
c ... Assume "call matvecM(n,x,y)" computes y = M*x
c ... Assume "call matvecA(n,x,y)" computes y = A*x
c ... Assume "call solve(n,rhs,x)" solves [A - sigma*M]*x = rhs
c ... Assume exact shifts are used
c ...
c ido = 0
c iparam(7) = 5
c
c %------------------------------------%
c | Beginning of reverse communication |
c %------------------------------------%
c 10 continue
c call _saupd ( ido, 'G', n, which, nev, tol, resid, ncv, v, ldv, iparam,
c & ipntr, workd, workl, lworkl, info )
c if (ido .eq. -1) then
c call matvecM (n, workd(ipntr(1)), workd(ipntr(2)))
c call matvecA (n, workd(ipntr(1)), temp_array)
c call _axpy (n, sigma, workd(inptr(2)), 1, temp_array, 1)
c call solve (n, temp_array, workd(ipntr(2)))
c go to 10
c else if (ido .eq. 1) then
c call matvecA (n, workd(ipntr(1)), workd(ipntr(2)))
c call _axpy (n, sigma, workd(inptr(3)), 1, workd(ipntr(2)), 1)
c call _copy (n, workd(inptr(2)), 1, workd(ipntr(3)), 1)
c call solve (n, workd(ipntr(3)), workd(ipntr(2)))
c go to 10
c else if (ido .eq. 2) then
c call matvecM (n, workd(ipntr(1)), workd(ipntr(2)))
c go to 10
c end if
c %------------------------------%
c | End of Reverse communication |
c %------------------------------%
c
c ... call _seupd to postprocess
c ... want the Ritz vectors set rvec = .true. else rvec = .false.
c call _seupd ( rvec, 'All', select, d, z, ldz, sigma, bmat,
c & n, which, nev, tol, resid, ncv, v, ldv, iparam,
c & ipntr, workd, workl, lworkl, info )
c stop
c end
c\EndDoc
c