ALLOCATE: Expand Array or String Dimensions

If memory runs short in running a script, the allocated array or string lengths can be expanded.

• increase_array_size
  to a new size of rows*columns:
  • bytes_allocated = ALLOCATE( name, columns [, rows])
  • if rows is omitted, its value is internally set to 1
  • ALLOCATE can be used to
    reshape_matrix
    by retaining the value of rows*columns.
    This includes the reshape of a vector to a matrix (rows present)
    or of a matrix to a vector. (rows not present)
  • REAL :: vec(1) ! initially 1 element only
  • ALLOCATE( vec, 10 ) ! increase to 10 elements
  • ALLOCATE( vec, 2* LEN(vec) ) ! double the current length
  • ALLOCATE( vec, 2, LEN(vec)/2 ) ! reshape vec to a 2 column matrix
  • ALLOCATE( vec, LEN(vec) ) ! reshape to a vector
  • rename_part_of_an_array
    • ALIAS( vec, 11, sub_vec, 5 ) ! rename vec(11...15) to sub_vec
    this has the functionality of
    equivalence
    in Fortran
  • the current values of name are retained when ALLOCATE is executed
  • ⇾ len(vec) to get the current length of vec
  • ⇾ Len_trim(vec) to get the length of vec when stripped of trailing zeros
• dynamically_increase_string_length
  to new_length:
  • bytes_allocated = ALLOCATE( name, new_length )
  • CHARACTER :: txt = 'abc' ! initial length is 3
  • ALLOCATE(txt, 20) ! txt length increased to 20
  • ALLOCATE(txt, 2* LEN(txt) ) ! txt length is doubled
  • named_substrings
    • ALIAS( string, 11, sub_string, 5 ) ! rename string(11:15) to sub_string
    this has the functionality of equivalence in Fortran
  • the current values of name are retained when ALLOCATE is executed
  • ⇾ len(string) to get the current length of string
  • ⇾ len_trim(string) to get the length of string when stripped of trailing blanks