HP OpenVMS Systems Documentation

HP Fortran for OpenVMS
Language Reference Manual

STRUCTURE /DATE/
  INTEGER*1  DAY, MONTH
  INTEGER*2  YEAR
END STRUCTURE

STRUCTURE /APPOINTMENT/
  RECORD /DATE/     APP_DATE
  STRUCTURE /TIME/  APP_TIME(2)
    INTEGER*1       HOUR, MINUTE
  END STRUCTURE
  CHARACTER*20      APP_MEMO(4)
  LOGICAL*1         APP_FLAG
END STRUCTURE

RECORD /APPOINTMENT/ NEXT_APP,APP_LIST(10)

For More Information:

• On specification of fields within structure declarations, see Section B.12.1.
• On structure declarations, see Section B.12.1.
• On UNION and MAP statements, see Section B.12.1.3.
• On the RECORD statement, see Section B.12.2.
• On alignment of data, see the HP Fortran for OpenVMS User Manual.

STRUCTURE /DATE/
  INTEGER*1 DAY, MONTH
  INTEGER*2 YEAR
END STRUCTURE

RECORD /DATE/ TODAY, THIS_WEEK(7)
STRUCTURE /APPOINTMENT/
  ...
  RECORD /DATE/ APP_DATE
END STRUCTURE

RECORD /APPOINTMENT/ MEETING

DO I = 1,7
  CALL GET_DATE (TODAY)
  THIS_WEEK(I) = TODAY
  THIS_WEEK(I).DAY = TODAY.DAY + 1
END DO
MEETING.APP_DATE = TODAY

This appendix describes the ASCII and DEC Multinational character sets that are available on OpenVMS systems.

For details on the Fortran 95/90 character set, see Section 2.2.

C.1 ASCII Character Set

Figure C-1 represents the ASCII character set (characters with decimal values 0 through 127). The first half of each of the numbered columns identifies the character as you would enter it on a terminal or as you would see it on a printer. Except for SP and HT, the characters with names are nonprintable. In Figure C-1, the characters with names are defined as follows:

The remaining half of each column identifies the character by the binary value of the byte; the value is stated in three radixes---octal, decimal, and hexadecimal. For example, the uppercase letter A has, under ASCII conventions, a storage value of hexadecimal 41 (a bit configuration of 01000001), equivalent to 101 in octal notation and 65 in decimal notation.

Figure C-1 Graphic Representation of the ASCII Character Set

The ASCII character set comprises the first half of the DEC Multinational Character Set. Figure C-2 represents the second half of the DEC Multinational Character Set (characters with decimal values 128 through 255). The first half of each of the numbered columns identifies the character as you would see it on a terminal or printer (these characters cannot be output on some older terminals and printers). The characters with names are nonprintable. In Figure C-2, the characters with names are defined as follows:

The shaded boxes in Figure C-2 indicate positions that are not part of the character set.

Figure C-2 Graphic Representation of the DEC Multinational Extension to the ASCII Character Set

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Several of the numeric intrinsic functions are defined by a model set for integers (for each integer kind used) and reals (for each real kind used). The bit functions are defined by a model set for bits (binary digits). This appendix describes these models.

For more information on the range of values for each data type (and kind), see the HP Fortran for OpenVMS User Manual.

D.1 Model for Integer Data

In general, the model set for integers is defined as follows:
i = s x <sum symbol><limits symbol>k=1^q w_k x r^k-1

The following values apply to this model set:

• i is the integer value.
• s is the sign (either +1 or --1).
• q is the number of digits (a positive integer).
• r is the radix (an integer greater than 1).
• w_k is a nonnegative number less than r.

The model for INTEGER(4) is as follows:
i = s x <sum symbol><limits symbol>k=1³¹ w_k x 2^k-1

The following example shows the general integer model for i = --20 using a base (r) of 2:

i = (-1) x (0 x 2⁰ + 0 x 2¹ + 1 x 2² + 0 x 2³ + 1 x 2⁴)
i = (-1) x (4 + 16)
i = -1 x 20
i = -20

The model set for reals, in general, is defined as one of the following:
x = 0

x = s x b^e x <sum symbol><limits symbol>k=1^p f_k x b^-k
The following values apply to this model set:

• x is the real value.
• s is the sign (either +1 or --1).
• b is the base (real radix; an integer greater than 1).

• p is the number of mantissa digits (an integer greater than 1). The number of digits differs depending on the real format, as follows:

  IEEE S_floating	24
  VAX F_floating	24
  IEEE T_floating	53
  VAX D_floating	53 1
  VAX G_floating	53

  ---

  ¹The memory format for VAX D_floating format is 56 mantissa digits, but computationally it is 53 digits. It is considered to have 53 digits by HP Fortran.
  

  ---

• e is an integer in the range e_min to e_max, inclusive. This range differs depending on the real format, as follows:

  	emin	emax
  IEEE S_floating	--125	128
  VAX F_floating	--127	127
  IEEE T_floating	--1021	1024
  VAX D_floating	--127	127
  VAX G_floating	--1023	1023

• f_k is a nonnegative number less than b (f₁ is also nonzero).

For x = 0 , its exponent e and digits f_k are defined to be zero.

The model set for single-precision real (REAL(4)) is defined as one of the following:
x = 0

x = s x 2^e x <left symbol><sum symbol><limits symbol>k=2²⁴ f_k x 2^-k<right symbol> -125 <= e <= 128

The following example shows the general real model for x = 20.0 using a base (b) of 2:

x = 1 x 2⁵ x (1 x 2^-1 + 0 x 2^-2 + 1 x 2^-3)
x = 1 x 32 x (.5 + .125)
x = 32 x (.625)
x = 20.0

The model set for bits (binary digits) interprets a nonnegative scalar data object of type integer as a sequence, as follows:
j = <sum symbol><limits symbol>k=0^s-1 w_k x 2^k
The following values apply to this model set:

• j is the integer value.
• s is the number of bits.
• w_k is a bit value of 0 or 1.

The bits are numbered from right to left beginning with 0.

The following example shows the bit model for j = 1001 (integer 9) using a bit number (s) of 4:

1 0 0 1
<swarrow symbol> <downarrow symbol> <downarrow symbol> <searrow symbol>
w_3 w_2 w_1 w_0

j = (w_0 x 2⁰) + (w_1 x 2¹) + (w_2 x 2²) + (w_3 x 2³)
j = 1 + 0 + 0 + 8
j = 9