> Dick Hendrickson wrote:

>> Gib Bogle wrote:

>>> Dick Hendrickson wrote:

>>>> Gib Bogle wrote:

>>>>> Hi,
>>>>> I'd like to know the fastest way to do a check on all elements of a
>>>>> slice of an array, looking for any occurrence of a particular
>>>>> condition. To be precise:
>>>>>
>>>>> fu(NX,NY,NZ) is an array of derived type, something like
>>>>>
>>>>> type fu_type
>>>>> integer :: bar
>>>>> integer :: status
>>>>> ...
>>>>> end type
>>>>>
>>>>> type(fu_type) :: fu(NX,NY,NZ)
>>>>>
>>>>> For a given x, and a status value stat0 I want to determine whether
>>>>> there is any (y,z) 1<=y<=NY, 1<=z<=NZ, such that
>>>>> fu(x,y,z)%%status /= stat0
>>>>>
>>>>> Is there a clever way to use the ANY intrinsic for this, or do I
>>>>> have to use dumb loops?

>>>> Depends on what you mean by "fastest". If the condition is an
>>>> "unusual" condition, than letting the compiler generate code for the
>>>> ANY intrinsic is almost always fastest. If the condition "almost
>>>> always" occurs, then a DO loop with a short circuit exit on the
>>>> first occurrence is likely to be fastest.
>>>>
>>>> The difference between "unusual" and "almost always" is processor
>>>> and compiler dependent.
>>>>
>>>> Dick Hendrickson

>>>
>>> Right. In my case conditions span the whole gamut, so there is no
>>> clear winner, I think.

>> I was going to whimsically suggest that you write it both ways in an
>> if-else block, using COUNT (test expression) < small_number as the IF
>> condition. That way you could get the fastest version either way (at
>> the cost of doubly computing everything). Then a serious idea popped
>> up, try experimenting with FIRSTLOC. That will possibly short-circuit
>> the tests when it finds a true instance. But, it's also likely that
>> the compiler will generate efficient code (unrolling, pipelined
>> execution, whatever) for the implied loop. Again, it will be hardware
>> and compiler dependent; but, you might be surprised.
>>
>> Dick Hendrickson

>
> To my surprise, ifort doesn't know about FIRSTLOC. Is this a new
> intrinsic?