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Ted Stern wrote: > Naomi was specifically asking how to avoid slowdowns due to use of > pointers. > On 06/25/2010 12:44 AM, Van Snyder wrote: > Here's how I solve it, rather than trying to outwit the compiler's > memory allocator. > [...] > When the CONTIGUOUS attribute is available in all the compilers I use, > I'll add it to the dummy argument declarations. > Regarding POINTER: Pointers have two disadvantages. (a) They have to regarded as noncontiguous by the compiler (unless they have the CONTIGUOUS attribute) and (b) a pointer might alias with another pointer or with a variable with TARGET attribute. Both the aliasing and noncontiguity forces the compiler to generate much slower code. For instance, the compiler might unnecessarily use temporary arrays, do copy-in/copy-out, assume strides, not optimizing away useless assignments etc. Thus, you should try to avoid POINTERS. Regarding Van's assumed-shaped dummies: As a work around, you could declare the dummy arguments as ALLOCATABLE. In this case, the compiler knows (or should know ;-) that the memory is contiguous. And instead of waiting until all compilers have the CONTIGUOUS attribute, you could use a preprocessor and conditionally define: #define CONTIGUOUS ,contiguous At least one of the latest Cray compilers and the gfortran (4.6 developer trunk) support the CONTIGUOUS attribute; I wouldn't be surprised if the next release of other vendors would have it as well. Tobias