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Cray

Cray CF77 and CF90

Fortran 90 properties already in CF77
Cray CF 90
System parameters on the Cray using CF90
Cray compiler on Non-Cray Computers
Information for local Cray users
Link to Cray Research, Inc.

Fortran 90 properties already in CF77.

Cray has a full Fortran 90 system available, but many of the new commands in Fortran 90 were already available in Cray Fortran 77, since Cray Research has been active in the development of the new standard. The array concepts are almost entirely included, since this area is close to Cray's general interest in vectorization and parallelization. See articles in CRAY CHANNELS, Fall 1992, (Vol. 14, No. 4), pp. 18-21.

For the present CF77 version 6.0 the following is already included:

Basic properties:

The special characters ", ! and _ are included.
The special character @ is also included but it is used by the system for special purposes.
The accepted line length can be switched from 72 to 80 characters.
Comments can start with a ! anywhere on the line except in position 6.
A statement can have up to 99 continuation lines.
A variable name (identifier) can have up to 31 characters, including the special character _.
Character strings can be delimited with either ' or ".
Octal and hexadecimal constants are available, and also bit operations according to Appendix 3, item 14.
A repetition factor for new lines has been added, that is for / in FORMAT.
Only the old form (fix form) of the source code is available.

Control statements:

DO, DO WHILE, END DO and WHERE, are available, but not EXIT and CYCLE.

Specifications:

IMPLICIT NONE and INCLUDE are available.
The NAMELIST functionality is available, but it can have another form, in addition to the one from Fortran 90.
The new type of specifications with :: is not available.

File operations.

All the new specifications to OPEN and INQUIRE are available.

Intrinsic functions:

The bit manipulation functions (Appendix 5, item 10) and the bit copy subroutine MVBITS are available, together with the following array functions: MERGE, PACK, SPREAD, UNPACK, RESHAPE, SUM, PRODUCT, MAXVAL, MINVAL, COUNT, ANY, ALL, TRANSPOSE, EOSHIFT, CSHIFT, MAXLOC, MINLOC, MATMUL and DOT_PRODUCT.
In addition the three bit manipulation functions from HPF are available.

Arrays:

Adjustable arrays, assumed-size arrays, automatic arrays, array sections and array assignments are available.
The command ALLOCATABLE is not available.

Additional concepts:

Recursion is available with certain special considerations, no RESULT clause is required.
Pointers are available but they are defined in a different way, compared with Fortran 90.

You have to be careful with both recursion and pointers on the Cray. Pointers in Fortran 90 and Cray Fortran are discussed in the article "Fortran 90 Pointers vs. "Cray" Pointers" by Jeanne Martin in the Fortran Forum, Vol. 11, No. 2, pp. 17 - 23, June 1992.

Removed extensions:

Of compatibility reasons the abbreviation DOUBLE for DOUBLE PRECISION and the specification DOUBLE COMPLEX were removed. Some system commands have also been changed.

Cray CF 90

I here list the most important switches to the compilation command for the Cray CF 90 Programming Environment.

   -c               compilation only (no linking)
   -C               creates an information file
   -d		    disables compiling options
   -e		    enables compiling options
   -f fixed         the old form of the source code
   -f free          the new form of the source code
   -g               generates information for debugging
   -G               more general debugging
   -i               decides on integer length
   -I incldir       Fortran 90 looks automatically for 
		    files to INCLUDE in the present directory, 
		    in directories in the I-list and in 
		    /usr/local/lib/f90 
   -l               linking of a library
   -Ldir            Add dir to the list of directories 
		    for library routines
   -m 		    specifies the level for error messages
   -M 		    used to suppress error messages
   -N		    specifies 72 or 80 colums for the fixed form source code
		    For free source code 132 is always valid
   -o               naming the output file
   -O		    optimization level
   -p pathname      Fortran 90 looks automatically for 
		    modules in the present directory, 
		    in directories in the I-list and in 
		    /usr/local/lib/f90
   -r               produces a compilation list 
 
   -S               produces source code in assembler
   -v               give comment about how the compilation 
		    is proceeding
   -V               gives the compiler's version number
   -Wl              sens information to the linker segldr

It can be mentioned here that Cray CF90 permits the use of REAL*8 instead of REAL and REAL*16 instead of DOUBLE PRECISION . The use of these notations should be avoided.

System parameters on the Cray using CF90.

System parameters on the Cray, using the Cray Fortran 90 compiler are given here. Compare with the NAG table. Note that Cray uses the number of bytes for the KIND value. Cray also permits the values 1, 2 and 4 for logical variables (with the same result as the default value 8), the values 1, 2, 4, 6 and 8 for integers and the values 4, 8 and 16 for real and complex variables. The notation half for the REAL case with KIND = 4 is my own, and so are also the notations int7, int15, int31, int46 and int63.

Remark. Our tests indicate that half is not implemented completely on the Cray Y-MP, in reality you get variables of the usual precision (called single below). Information from Cray Research indicate that half is introduced in order to obtain a certain compatibility with Cray T3D, on which system that precision (half) really exists.

WARNING: I will have to double check this table at each revision of the compiler! The parameters are being changed by Cray. The present system is Cray F90 Version 1.0 (1.56 or 1.70), CRAY CF 90 Version 1.0.1.0 (779005) or 1.0.2.0 (047431). The parameters below are also valid for Cray CF90 Version 2.0.0.0.

See also the numerical inquiry functons in Appendix 5.8.

LOGICAL              Default
  KIND number =            8
 
INTEGER                Default           int7          int15
 KIND number =               6              1              2
      digits =              46              7             15
       radix =               2              2              2
       range =              13              2              4
        huge =  70368744177663            127          32767
    bit_size =              46              8             16
 
INTEGER                  int31          int46               int64
 KIND number =               4              6                   8
      digits =              31             46                  63
       radix =               2              2                   2
       range =               9             13                  18
        huge =      2147483647 70368744177663 9223372036854775807
    bit_size =              32             46                  46
 
REAL                        half  Default,single          double
  KIND number =                4               8              16
       digits =               24              47              96
  maxexponent =             8189            8189            8190
  minexponent =            -8188           -8188           -8189
    precision =                6              13              28
        radix =                2               2               2
        range =             2465            2465            2465
      epsilon =   0.11920929E-06   0.14210855-13  0.25243549E-28
         tiny =  0.73344155-2465 0.73344155-2465 0.73344155-2465  
         huge =  0.13634352+2466 0.13634352+2466 0.13634352+2466 
  
COMPLEX                    half  Default,single         double
  KIND number =               4               8             16
    precision =               6              13             28
        range =            2465            2465           2465

Cray compiler on Non-Cray Computers

The Cray system is also available on other systems, especially on the Sun SPARC. For further information see CraySoft Fortran 90 Programming Environment.

Information for local Cray users

NSC has made the Cray Fortran 77 and Fortran 90 manuals available on line with a system described in Swedish in Newsletter 109, item 3.

Back to Appendix 6

Last modified: 23 October 1996
boein@nsc.liu.se