为 ARPACK 中的数组 ipntr 赋值
我试图弄清楚如何将值分配给 ARPACK 中名为 ipntr 的数组，该数组存储指针。我对 Fortran 比较陌生，我无法弄清楚这个数组的值最初是如何设置的。我正在查看的代码是与 ARPACK 一起分发的不对称驱动程序示例 dndrv1.f ，我不理解的部分如下
program dndrv1
integer maxn, maxnev, maxncv, ldv
parameter (maxn=256, maxnev=12, maxncv=30, ldv=maxn)
c
c %--------------%
c | Local Arrays |
c %--------------%
c
integer iparam(11), ipntr(14)
logical select(maxncv)
Double precision
& ax(maxn), d(maxncv,3), resid(maxn),
& v(ldv,maxncv), workd(3*maxn),
& workev(3*maxncv),
& workl(3*maxncv*maxncv+6*maxncv)
c
c %---------------%
c | Local Scalars |
c %---------------%
c
character bmat*1, which*2
integer ido, n, nx, nev, ncv, lworkl, info, j,
& ierr, nconv, maxitr, ishfts, mode
Double precision
& tol, sigmar, sigmai
logical first, rvec
c
c %------------%
c | Parameters |
c %------------%
c
Double precision
& zero
parameter (zero = 0.0D+0)
c
c %-----------------------------%
c | BLAS & LAPACK routines used |
c %-----------------------------%
c
Double precision
& dlapy2, dnrm2
external dlapy2, dnrm2, daxpy
c
c %--------------------%
c | Intrinsic function |
c %--------------------%
c
intrinsic abs
write(*,*) ipntr
写入语句的结果是：
1606679396 32767 1606696480 32767 1606918048 32767 0 0 0 0 0 0 0 0
显然没有什么比ipntr(1) = 1606679396 那么这些值是如何分配的呢？
谢谢
I am trying to figure out how values are assigned to the array called ipntr, which stores pointers, in ARPACK. I am relatively new to fortran and I can't figure out exactly how the values of this array are initially set. The code I am looking at is an unsymmetric driver example dndrv1.f distributed with ARPACK and the portion I am not understanding is as follows
program dndrv1
integer maxn, maxnev, maxncv, ldv
parameter (maxn=256, maxnev=12, maxncv=30, ldv=maxn)
c
c %--------------%
c | Local Arrays |
c %--------------%
c
integer iparam(11), ipntr(14)
logical select(maxncv)
Double precision
& ax(maxn), d(maxncv,3), resid(maxn),
& v(ldv,maxncv), workd(3*maxn),
& workev(3*maxncv),
& workl(3*maxncv*maxncv+6*maxncv)
c
c %---------------%
c | Local Scalars |
c %---------------%
c
character bmat*1, which*2
integer ido, n, nx, nev, ncv, lworkl, info, j,
& ierr, nconv, maxitr, ishfts, mode
Double precision
& tol, sigmar, sigmai
logical first, rvec
c
c %------------%
c | Parameters |
c %------------%
c
Double precision
& zero
parameter (zero = 0.0D+0)
c
c %-----------------------------%
c | BLAS & LAPACK routines used |
c %-----------------------------%
c
Double precision
& dlapy2, dnrm2
external dlapy2, dnrm2, daxpy
c
c %--------------------%
c | Intrinsic function |
c %--------------------%
c
intrinsic abs
write(*,*) ipntr
The result of the write statement is:
1606679396 32767 1606696480 32767 1606918048 32767 0 0 0 0 0 0 0 0
Obviously there is nothing like ipntr(1) = 1606679396 so how have these values been assigned?
Thanks
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如果变量没有分配到任何地方，那么它们的值将由内存中恰好驻留的任何随机字节序列决定。您应该看到重新运行该程序将产生不同的输出序列。
If the variables aren't assigned anywhere, then their values will be determined by whatever random byte sequence happens to reside in memory. You should see that re-running the program will produce a different output sequence.