Re: Fortran array optimizations


Richard Maine wrote:
On Mon, 8 Jan 2007 08:08:22 -0800, highegg wrote
(in article <1168272502.910316.40810@xxxxxxxxxxxxxxxxxxxxxxxxxxx>):

i know that compilers can perform "common subexpression elimination",...
...
with xmin,xmax real scalars and x,z,y real vectors.
do i=1,n
z(i) = interpolate(x(i),xmin,xmax,1/y)
end do

which of course worked fine, but I asked myself:
Will the compiler evaluate 1/y to a temporary array in each cycle, or
will it perform an "array-valued common subexpression elimination" and
evaluate 1/y in advance?

Well, 1/y is not valid syntax at all if y is an array.

Why? If y a real vector of length N, isn't 1/y the same? A scalar is
conformable with an array.

.

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