Why define PI = 4*ATAN(1.d0)

What is the motivation for defining PI as

PI=4.D0*DATAN(1.D0)

within Fortran 77 code? I understand how it works, but, what is the reasoning?

Solution

This style ensures that the maximum precision available on ANY architecture is used when assigning a value to PI.

gfortran compiler bug?
Are Fortran control characters (carriage control) still implemented in compilers?
Fortran sample code assemble
Will Fortran compilers completely remove always false if-blocks when optimizing?
compile fortran program with 2 compilers
gfortran execution bug when compiled with optimization if some variable is declared "intent(out)"
OpenMP's OMP_SET_NUM_THREADS() not working as expected
How to get the Q from the QR factorization output?
Return a string array from a C++ function to Fortran
Compilation failed when using gfortran flag default-real-8 and stdlib
How do I set the correct compiler to use the -fastsee option
Intel Visual Fortran Compiler name mangling, is my compiler just being crazy?
Why Segmentation fault is happening in this openmp code?
How do I see the assembler files in CMake?
storing a procedure pointer within a type in Fortran
fortran derived type with parameterized len
Fortran type mismatch error
How to make an OpenMP parallel code to run serially by default?
Program compiled with gfortran, how to recompile with ifort?
why .mod files differ after every time i compile a .f file
How does BLAS get such extreme performance?
syntax error while compiling with ifort 11.0
Fortran if statement errors
Definitive length of primitive C and Fortran types
How to use multithreaded FFTW inside an OpenMP Fortran code
How do I write a loop in a gdb script?
Are Fortran, Cobol, Basic and Forth high level programming languages?
why is maximum single-line length limited to 132 characters in Fortran Standard?
Reading binary data file in python for analysis
"wrapping" subroutines in Fortran