Array Terminology

Examples of declarations:

    REAL, DIMENSION(15)      :: X
    REAL, DIMENSION(1:5,1:3) :: Y, Z

The above are explicit-shape arrays.

If the lower bound is not explicitly stated it is taken to be 1.

Terminology:

• rank -- the number of dimensions up to and including 7 dimensions. X has rank 1, Y and Z have rank 2.
• bounds -- upper and lower limits of indices, an unspecified bound is 1. X has lower bound 1 and upper bound 15, Y and Z have lower bounds of 1 and 1 with upper bounds 5 and 3.
• extent -- number of elements in dimension (which can be zero). X has extent 15, Y and Z have extents 5 and 3.
• size -- either the total number of elements or, if particular dimension is specified, the number of elements in that dimension. All arrays have size 15.
• shape -- rank and extents. X has shape (/15/), Y and Z have shape (/5,3/).
• conformable -- two arrays are conformable if they have the same shape -- for operations between two arrays the shapes (of the sections) must (generally) conform (just like in mathematics). Y and Z have the same shape so they conform.
• there is no storage association for Fortran 90 arrays.

Explicit-shape arrays can have symbolic bounds so long as they are initialisation expressions -- evaluatable at compile time.

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