🚀 go-pugleaf

On Fri, 8 Jan 1993 13:46:12 GMT, pfennige@scsun.unige.ch (PFENNIGER Daniel) said:


PFENNIGER> Is it true that a Fortran-90 programme inverting matrix A would be:
PFENNIGER>       B = 1./A

No.  That would be a legal statement, but it makes each element of B
the inverse of the corresponding element of A.  The f90 arrays are
better thought of as "arrays" than as "matrices".  In particular,
all the operations are element-by-element.  There is a standard
matmul subroutine for the usual matrix multiplication, but there is
no matrix inversion.

I wasn't on the committee at the time, but I believe the rationale was
that there was no single matrix inversion technique good for all
situations, and that numerically-oriented users were better off
choosing a particular, appropriate one than whatever the vendor
happened to implement (which might be different on different
platforms).

You (or a library writer) can make a "matrix" (or whatever you want to
call it) user-defined type and define division for it such that the
above sample line would do the matrix inversion, but such a type
isn't part of the base language.

--
--
Richard Maine
maine@altair.dfrf.nasa.gov