PENF Documentation

🔢

Portable Kind Parameters

Integer and real kind parameters for 1, 2, 4, 8, and 16-byte representations — guaranteed portable across compilers and architectures.

🔄

Number ↔ String Conversion

Comprehensive str(), strz(), cton(), bstr() and bcton() procedures for casting between numbers and strings, including binary representations.

📐

Format Definitions & Limits

Ready-made format strings (FI*P, FR*P) and min/max representable values for every supported kind parameter.

🖥️

Endianness Detection

Built-in check_endian() procedure to detect big- or little-endian byte ordering at runtime.

🧩

Fortran 2003+ Compliant

Fully standard-compliant library. Tested with GNU (≥ 4.9.2) and Intel (≥ 12.x) compilers.

🆓

Free & Open Source

Multi-licensed — GPLv3 for FOSS projects, BSD 2/3-Clause or MIT for commercial use. Any contributor is welcome.

Quick start

fortran

use penf
call penf_init

real(R8P)    :: x = -1.0_R8P
integer(I4P) :: n = 42_I4P

print FR8P, x !  -0.100000000000000E+001
print FI4P, n !          42

Real kinds

Parameter	Precision	Range	Size
`R16P`	33 digits	$[10^{- 4931}, 10^{+ 4931} - 1]$	128 bit
`R8P`	15 digits	$[10^{- 307}, 10^{+ 307} - 1]$	64 bit
`R4P`	6 digits	$[10^{- 37}, 10^{+ 37} - 1]$	32 bit

Parameter

Precision

Range

Size

R16P

33 digits

[10^{- 4931}, 10^{+ 4931} - 1]

128 bit

R8P

15 digits

[10^{- 307}, 10^{+ 307} - 1]

64 bit

R4P

6 digits

[10^{- 37}, 10^{+ 37} - 1]

32 bit

Integer kinds

Parameter	Range	Size
`I8P`	$[- 2^{63}, + 2^{63} - 1]$	64 bit
`I4P`	$[- 2^{31}, + 2^{31} - 1]$	32 bit
`I2P`	$[- 2^{15}, + 2^{15} - 1]$	16 bit
`I1P`	$[- 2^{7}, + 2^{7} - 1]$	8 bit

Parameter

Range

Size

I8P

[- 2^{63}, + 2^{63} - 1]

64 bit

I4P

[- 2^{31}, + 2^{31} - 1]

32 bit

I2P

[- 2^{15}, + 2^{15} - 1]

16 bit

I1P

[- 2^{7}, + 2^{7} - 1]

8 bit

Format Strings

Each kind has a matching format string for print / write statements:

Kind	Format string	Example output
`R16P`	`FR16P = '(E45.36E4)'`	`-0.100000000000000000000000000000000000E+0001`
`R8P`	`FR8P = '(E25.17E3)'`	`-0.10000000000000000E+001`
`R4P`	`FR4P = '(E16.9E2)'`	`-0.100000000E+01`
`I8P`	`FI8P = '(I20)'`	`-1`
`I4P`	`FI4P = '(I11)'`	`-1`
`I2P`	`FI2P = '(I6)'`	`-1`
`I1P`	`FI1P = '(I4)'`	`-1`

Kind

Format string

Example output

R16P

FR16P = '(E45.36E4)'

-0.100000000000000000000000000000000000E+0001

R8P

FR8P = '(E25.17E3)'

-0.10000000000000000E+001

R4P

FR4P = '(E16.9E2)'

-0.100000000E+01

I8P

FI8P = '(I20)'

-1

I4P

FI4P = '(I11)'

-1

I2P

FI2P = '(I6)'

-1

I1P

FI1P = '(I4)'

-1

PENFPortability Environment for Fortran Poor People

Portable Kind Parameters

Number ↔ String Conversion

Format Definitions & Limits

Endianness Detection

Fortran 2003+ Compliant

Free & Open Source

Quick start

Real kinds

Integer kinds

Format Strings

Authors

Copyrights

PENFPortability Environment for Fortran Poor People

Portable Kind Parameters

Number ↔ String Conversion

Format Definitions & Limits

Endianness Detection

Fortran 2003+ Compliant

Free & Open Source

Quick start ​

Real kinds ​

Integer kinds ​

Format Strings ​

Authors ​

Copyrights ​

Quick start

Real kinds

Integer kinds

Format Strings

Authors

Copyrights