C Library Functions  - M_units (3)

NAME
M_units(3fm) - [M_units::INTRO] convert between various physical units (LICENSE:MIT)

CONTENTS

Synopsis
Constants Synopsis
Description
Procedures
Constants
Notes
Examples

SYNOPSIS

procedure definitions: 

      elemental real function c2f(celsius)
      elemental real function f2c(fahrenheit)


      elemental real|double function r2d(radians)
      elemental real|double function d2r(degrees)


      elemental real function feet_to_meters(feet)
      elemental real function meters_to_feet(meters)


      elemental real function sind(angle_in_degrees)
      elemental real function cosd(angle_in_degrees)
      elemental real function tand(angle_in_degrees)
      elemental real function asind(x)
      elemental real function acosd(x)
      elemental real function atand(x)
      elemental real function atan2d(x,y)


      elemental double function norm_angle_rad(radians)
      elemental real|double function norm_angle_deg(radians)


      subroutine cartesian_to_spherical(x,y,z,radius,inclination,azimuth)
      subroutine spherical_to_cartesian(radius,inclination,azimuth,x,y,z)
      subroutine cartesian_to_polar(x,y,radius,inclination)
      subroutine polar_to_cartesian(radius,inclination,x,y)

CONSTANTS SYNOPSIS

syntax: 

      function nan()
      function inf()
      function is_nan()
      function is_even()
Simple constants: 

    e,gamma,euler,golden_ratio,pi
    deg_per_rad, rad_per_deg
    c__m_per_sec, c__ft_per_sec

DESCRIPTION

M_units(3fm) is a Fortran module that collects together basic procedures that are used to convert between various physical units and common named constants.

The input values may be any standard scalar value supported by the anyscalar_to_real(3f) function (real,integer,doubleprecision) within the range allowed by the function.

PROCEDURES

Angular Units

o d2r: Convert degrees to radians
o r2d: Convert radians to degrees

Temperature

o c2f: Convert Celsius to Fahrenheit
o f2c: Convert Fahrenheit to Celsius

Distance

o feet_to_meters: Convert feet to meters
o meters_to_feet: Convert meters to feet

REAL trig functions where input is in angular degrees instead of radians

o elemental real function sind(angle_in_degrees)
o elemental real function cosd(angle_in_degrees)
o elemental real function tand(angle_in_degrees)
o elemental real function asind(x)
o elemental real function acosd(x)
o elemental real function atand(x)
o elemental real function atan2d(x,y)

Normalize angles into specific ranges

o elemental double function norm_angle_rad(angle_in_radians)
o elemental real|double function norm_angle_deg(angle_in_degrees)

Coordinates

o cartesian_to_spherical: Convert cartesian coordinates to spherical
o spherical: Convert spherical coordinates to cartesian
o cartesian_to_polar: Convert cartesian coordinates to polar
o polar: Convert polar coordinates to cartesian

Note that your compiler is less likely to inline small procedures in a module than it would statement functions or CONTAINED functions.

CONSTANTS

c__m_per_sec
  Speed of light in a vacuum
c__ft_per_sec
  Speed of light in a vacuum "deg_per_rad" "rad_per_deg"
e The base of the natural logarithm system. "e" was named in honor of Euler, but is known as Napier’s constant. "euler"
gamma The Euler-Mascheroni constant is often denoted by a lower-case Gamma. "golden_ratio"
pi The ratio of the circumference of a circle to the diameter of the circle

NOTES

Gamma is defined as 

   Gamma = limit ( M -> Infinity ) ( Sum ( 1 <= N <= M ) 1 / N ) - Log ( M )

EXAMPLES
Simple usage example: 

   program demo_M_units
   use M_units, only : r2d, d2r
   use M_units, only : f2c, c2f
   use M_units, only : sind, cosd, tand
   use M_units, only : asind, acosd, atand, atan2d
   !!
   use M_units, only : pi8=>pi
   use M_units, only : e,euler,golden_ratio,deg_per_rad,rad_per_deg
   use M_units, only : c__m_per_sec, c__ft_per_sec
   !!
   implicit none
   real pi
   pi=pi8
   write(*,*)r2d([0.0,PI/4.0,PI/2.0,3.0*PI/2.0,PI])
   write(*,*)d2r([0.0,45.0,90.0,135.0,180.0])
   write(*,*)f2c([-40.0,32.0,212.0])
   write(*,*)c2f([-40.0,0.0,100.0])
   write(*,*)PI
   write(*,*)E
   !!
   write(*,101) "Napier’s constant (e) is about ",e
   write(*,101) "The Euler-Mascheroni constant (euler or gamma) is about ",euler
   write(*,101) "pi (pi) is about ",pi8
   write(*,101) "The Golden Ratio (golden_ratio) is about ",golden_ratio
   write(*,101) "Deg_Per_Rad is about ",Deg_Per_Rad
   write(*,101) "Rad_Per_Deg is about ",Rad_Per_Deg
   !!
   write(*,101) "Speed of light in a vacuum (m/sec)       ", c__m_per_sec
   write(*,101) "Speed of light in a vacuum (ft/sec)      ", c__ft_per_sec
   !!
   101 format(a,t57,g0)
   !!
   end program demo_M_units
Results: 

   >   0.00000000       45.0000000       90.0000000       270.000000       180.000000
   >   0.00000000      0.785398185       1.57079637       2.35619450       3.14159274
   >  -40.0000000       0.00000000       100.000000
   >  -40.0000000       32.0000000       212.000000
   >   3.14159274
   >   2.7182818284590451
   >Napier’s constant (e) is about                          2.7182818284590451
   >The Euler-Mascheroni constant (euler or gamma) is about 0.57721566490153287
   >pi (pi) is about                                        3.1415926535897931
   >The Golden Ratio (golden_ratio) is about                1.6180339887498949
   >Deg_Per_Rad is about                                    57.295779513082323
   >Rad_Per_Deg is about                                    0.17453292519943295E-001
   >Speed of light in a vacuum (m/sec)                      299792458.00000000
   >Speed of light in a vacuum (ft/sec)                     983571056.00000000

Nemo Release 3.1 M_units (3) February 23, 2025
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