pm_arrayCompareLex Module Reference

This module contains procedures and generic interfaces for performing lexicographic comparisons of two arrays of similar type, kind, and rank.
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Data Types
interface	operator(.lge.)
	Generate and return the result of the lexicographic comparison of two input objects of the same type, kind, and rank using the >= operator. More...
interface	operator(.lgt.)
	Generate and return the result of the lexicographic comparison of two input objects of the same type, kind, and rank using the > operator. More...
interface	operator(.lle.)
	Generate and return the result of the lexicographic comparison of two input objects of the same type, kind, and rank using the <= operator. More...
interface	operator(.llt.)
	Generate and return the result of the lexicographic comparison of two input objects of the same type, kind, and rank using the < operator. More...

Variables
character(*, SK), parameter	MODULE_NAME = "@pm_arrayCompareLex"

Detailed Description

This module contains procedures and generic interfaces for performing lexicographic comparisons of two arrays of similar type, kind, and rank.

A lexicographical comparison is the kind of comparison generally used to sort words alphabetically in dictionaries.
It involves comparing sequentially the elements that have the same position in both ranges against each other until one element is not equivalent to the other.
The result of comparing these first non-matching elements is the result of the lexicographical comparison.
If the two arrays are of different lengths but are equivalent up to the last common element comparison, then the result of the comparison of the sizes of the two arrays will be returned.

Note

The lexicographical order is also known as the Dictionary order because the words in a dictionary are commonly sorted lexicographically.

Note that the Fortran language intrinsically defines the lexicographic comparison of scalar character objects.
However, the intrinsic Fortran definition pads the smaller array with blanks before comparison.
Therefore, as long as the extra elements of the longer array correspond to characters that appear after the blank character in the collating sequence of the processor, the intrinsic Fortran scalar character comparison matches the above definition for lexicographic comparison that is used in this module.

Note that the result of a lexicographic comparison is always a scalar regardless of the ranks of the objects being compared.

By definition, a lexicographic comparison can only be defined for objects of the same rank.

By default, a .true. value is assumed to be larger than the .false. value in this module.
Therefore, .false. < .true. evaluates to .true..

By default, the two components of complex numbers are also compared lexically in this module.
For example, (1.,2.) < (1.,1.) evaluates to .false. while (1.,2.) < (2.,1.) evaluates to .true..

Test:

test_pm_arrayCompareLex

Todo:

Normal Priority: A generic interface for supplying a user-defined arbitrary comparison operator should be added.

Todo:

Normal Priority: Ideally, a procedure with unlimited polymorphic arguments could be also added for lexical comparison of all types of input arrays, albeit with a user-defined operator supplied to the procedure.

Final Remarks ⛓

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Copyright

Computational Data Science Lab

Author:

Amir Shahmoradi, September 1, 2017, 12:00 AM, Institute for Computational Engineering and Sciences (ICES), The University of Texas at Austin

Variable Documentation

MODULE_NAME

character(*, SK), parameter pm_arrayCompareLex::MODULE_NAME = "@pm_arrayCompareLex"

Definition at line 77 of file pm_arrayCompareLex.F90.