It is a common module which defines some common used numerical or physical constants. They are as follows:

• Numerical precision: sp, dp
• File units: mystd, myout, mytmp
• Numerical constants (real number): pi, zero, one, two, half
• Numerical constants (small number): eps6, eps8, epst, epss
• Numerical constants (complex number): czi, cone, czero
• Physical constants: ev2k, ry2e, ha2e

We always need to import this module.

Type

module

Source

src/m_constants.f90

Usage

(1) Import constants module completely.

program test
    use constants

    implicit none

    real(dp) :: A
    A = one
end program test

(2) Import constants module partially.

program test
    use constants, only : dp
    use constants, only : one

    implicit none

    real(dp) :: A
    A = one
end program test