CIRCLE_POINTS
Write Circle Points to a File

CIRCLE_POINTS is an executable FORTRAN90 program, using double precision arithmetic, which calculates points equally spaced on a circle and writes them to a file.

Usage:

circle_points number r x y angle1 angle2 file

computes number points on a circle of radius r and center (x,y), from angle angle1 (in degrees) to angle2, and writes the results to the file file.

Related Programs:

GEOMETRY is a FORTRAN90 library which contains a number of routines for sampling points on various geometric shapes.

PLOT_POINTS is an executable FORTRAN90 program that can make a plot of the points.

RANDOM_DATA is a library which contains a number of routines for sampling random points in or on various geometric shapes.

Source Code:

• circle_points.f90, the source code.
• circle_points.csh, commands to compile the source code.

Examples and Tests:

ARC is a set of 10 equally spaced points from 0 to 90 degrees.

• arc.txt, is the data file created by the command

  
              circle_points 10 5 5 2 0 90 arc.txt
            

• arc.png, is a PNG image of the points.

PENTAGON is a set of 6(!) equally spaced points from 0 to 360 degrees. This is the easiest way to get a pentagon, but you should really edit the file and remove the last point, since it repeats the first one. The alternative is to specify that the angles range from 0 to 288 degrees!

• pentagon.txt, is the data file created by the command

  
              circle_points 6 0 0 1 0 360 pentagon.txt
            

• pentagon.png, is a PNG image of the points.

List of Routines:

• MAIN is the main program for CIRCLE_POINTS.
• CH_CAP capitalizes a single character.
• CH_EQI is a case insensitive comparison of two characters for equality.
• CH_TO_DIGIT returns the integer value of a base 10 digit.
• GET_UNIT returns a free FORTRAN unit number.
• S_BLANK_DELETE removes blanks from a string, left justifying the remainder.
• S_TO_I4 reads an I4 from a string.
• S_TO_R8 reads an R8 from a string.
• TIMESTAMP prints the current YMDHMS date as a time stamp.
• TIMESTRING writes the current YMDHMS date into a string.
• WORD_EXTRACT extracts the next word from a string.

You can go up one level to the FORTRAN90 source codes.