"# Fortran"

tutorial: https://www.tutorialspoint.com/fortran/

launch.json / task.json: https://marketplace.visualstudio.com/items?itemName=ekibun.fortranbreaker https://qiita.com/implicit_none/items/d49c9fdf51c307d22819

Fortran - Variables:

• 1 Integer
  • It can hold only integer values.
• 2 Real
  • It stores the floating point numbers.
• 3 Complex
  • It is used for storing complex numbers.
• 4 Logical
  • It stores logical Boolean values.
• 5 Character
  • It stores characters or strings.

Fortran - Constants:

• 1 Literal constants
• 2 Named constants

Fortran - Operators

• 1 Arithmetic Operators
• 2 Relational Operators
• 3 Logical Operators

Fortran - Decisions

• 1 IF
• 2 Select case

Fortran - Loops

• 1 Loop Type & Description (do loop)
• 2 Loop Control Statements

Fortran - Numbers

• 1 Integer type
• 2 Real type
• 3 Complex type

The Range, Precision and Size of Numbers

Number of bits Maximum value Reason 64 9,223,372,036,854,774,807 (263)–1 32 2,147,483,647 (231)–1

Number of bits Largest value Smallest value Precision 64 0.8E+308 0.5E–308 15–18 32 1.7E+38 0.3E–38 6-9

Fortran - Characters

• type-specifier :: variable_name

Some Character Functions

• 1 len(string)
• 2 index(string,sustring)
• 3 achar(int)
• 4 iachar(c)
• 5 trim(string)
• 6 scan(string, chars)
• 7 verify(string, chars)
• 8 adjustl(string)
• 9 adjustr(string)
• 10 len_trim(string)
• 11 repeat(string,ncopy)

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Checking Lexical Order of Characters

• 1 lle(char, char)
• 2 lge(char, char)
• 3 lgt(char, char)
• 4 llt(char, char)

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Fortran - Strings

• type-specifier :: variable_name

Fortran - Arrays

• real, dimension(5) :: numbers

Array Intrinsic Functions

• Vector and matrix multiplication
• Reduction
• Inquiry
• Construction
• Reshape
• Manipulation
• Location

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Fortran - Dynamic Arrays

• real, dimension (:,:), allocatable :: darray

Fortran - Derived Data Types

• Title
• Author
• Subject
• Book ID

Fortran - Pointers

• integer, pointer :: p1 ! pointer to integer
• real, pointer, dimension (:) :: pra ! pointer to 1-dim real array
• real, pointer, dimension (:,:) :: pra2 ! pointer to 2-dim real array

Fortran - Basic Input Output

• read(,) item1, item2, item3...
• print *, item1, item2, item3
• write(,) item1, item2, item3...

Formatted Input Output

• I → integer

  • Target: This is used for integer output.
  • Format: ‘rIw.m’
  • Rule: If the field width is not large enough to accommodate an integer then the field is filled with asterisks.

• F → real number

  • Target: This is used for real number output.
  • Format: ‘rFw.d’
  • Rule: If the field width is not large enough to accommodate the real number then the field is filled with asterisks.

• E → real output (exponential notation)

  • Target: This is used for real output in exponential notation.
  • Format: rEw.d
  • Rule: In general, w ≥ d + 7.

• ES → real output (scientific notation)

  • Target: This is used for real output (scientific notation).
  • Format: ‘rESw.d’
  • Rule: expressionw ≥ d + 7

• A → character

  • Target: This is used for character output.
  • Format: ‘rAw’
  • Rule: If the field width is not large enough to accommodate the character string then the field is filled with the first ‘w’ characters of the string.

• X → space

  • Target: his is used for space output.
  • Format: ‘nX’
  • Rule: ‘n’ is the number of desired spaces.

• / → blank lines.

  • Target: Slash descriptor – used to insert blank lines.
  • Format: ‘/’
  • Rule: the next data output to be on a new line.

• Symbol & Description

  • c: Column number
  • d: Number of digits to right of the decimal place for real input or output
  • m: Minimum number of digits to be displayed
  • n: Number of spaces to skip
  • r: Repeat count – the number of times to use a descriptor or group of descriptors
  • w: Field width – the number of characters to use for the input or output

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Fortran - File Input Output

• open (unit = number, file = "name").

Specifier & Description

• 1 [UNIT=] u The unit number u could be any number in the range 9-99 and it indicates the file, you may choose any number but every open file in the program must have a unique number

• 2 IOSTAT= ios It is the I/O status identifier and should be an integer variable. If the open statement is successful then the ios value returned is zero else a non-zero value.

• 3 ERR = err It is a label to which the control jumps in case of any error.

• 4 FILE = fname File name, a character string.

• 5 STATUS = sta It shows the prior status of the file. A character string and can have one of the three values NEW, OLD or SCRATCH. A scratch file is created and deleted when closed or the program ends.

• 6 ACCESS = acc It is the file access mode. Can have either of the two values, SEQUENTIAL or DIRECT. The default is SEQUENTIAL.

• 7 FORM = frm It gives the formatting status of the file. Can have either of the two values FORMATTED or UNFORMATTED. The default is UNFORMATTED

• 8 RECL = rl It specifies the length of each record in a direct access file.

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• read ([UNIT = ]u, [FMT = ]fmt, IOSTAT = ios, ERR = err, END = s)
• write([UNIT = ]u, [FMT = ]fmt, IOSTAT = ios, ERR = err, END = s)

Fortran - Procedures

• function function name(arg1, arg2, ....) result (return_var_name)
  [declarations, including those for the arguments]
  [executable statements] end function [name]

• subroutine subroutine name(arg1, arg2, ....)
  [declarations, including those for the arguments]
  [executable statements]
  end subroutine [name]

Fortran - Modules

test3