M_calculator

parse mathematical expressions

The M_calculator(3f) module contains a basic expression parser and related convenience routines.

Expressions are similar to Fortran77 syntax except

• powers are processed from left to right so use parenthesis
• variable names are case-sensitive
• string variable names start with a dollar-sign,
• all numeric values are assumed to be DOUBLEPRECISION.

Note that although suitable for many uses, this is not a byte-code interpreter and is designed for parsing basic unique expressions, not for high volume repetition of the computations on a large volume of data.

The original dates back a long time, but it still works.

Example

program demo_dnum0
use M_calculator, only: dnum0
implicit none
doubleprecision              :: x, y, z, answer
integer                      :: i
character(len=:), allocatable :: strings(:)

   strings = [character(len=128) :: &
   '20/3.4                       ', &
   'CI=10*sin(3.1416/4)          ', &
   'a=CI**2+sqrt(90)             ', &
   'x=a/CI-atan(a)               ', &
   'y=x+CI/333                   ', &
   '                             ']

   do i = 1, size(strings)
      answer = dnum0(strings(i))
      write(*,'(*(g0))')answer,' = ',strings(i)
   enddo

   x = dnum0('x')
   y = dnum0('y')
   z = dnum0('CI')
   write (*, *) x, y, z

end program demo_dnum0

Results:

 > 5.8823529411764710 = 20/3.4
 > 7.0710807985947346 = CI=10*sin(3.1416/4)
 > 59.487016640760288 = a=CI**2+sqrt(90)
 > 6.8587316018816180 = x=a/CI-atan(a)
 > 6.8799660787542747 = y=x+CI/333
 > 0.0000000000000000 =
 >    6.8587316018816180        6.8799660787542747        7.0710807985947346

Documentation

• The user documentation describes the many functions available.

• The code was run through ford(1) to produce a developers' document.

• github action status

Build with gmake(1)

    git clone https://github.com/urbanjost/M_calculator.git
    cd M_calculator/src
    # change Makefile if not using one of the listed compilers

    # for gfortran
    make clean
    make F90=gfortran gfortran

    # for ifort
    make clean
    make F90=ifort ifort

    # for nvfortran
    make clean
    make F90=nvfortran nvfortran

This will compile the M_calculator module and build all the example programs from the document pages in the PROGRAMS/ sub-directory.

Build with fpm(1)

(registered at the fpm(1) registry )

Alternatively, download the github repository and build it with fpm ( as described at Fortran Package Manager )

    git clone https://github.com/urbanjost/M_calculator.git
    cd M_calculator
    fpm build
    fpm test

or just list it as a dependency in your fpm.toml project file.

    [dependencies]
    calculator        = { git = "https://github.com/urbanjost/M_calculator.git" }

Find M_calculator on github