Newbie Programming Confusion

[smp]

Hello all,

As a newbie with my Prime, I am slowly attempting different things to learn how to do programming on it (I'm having great fun with this!).

For most of my programs so far, I have dug out old BASIC programs that I have had running before on other vintage computer systems that I have.

My latest program is a simple one that calculates the value of Pi by adding up the sides of a polygon inscribed within a circle. This program comes from an old article from Creative Computing back in 1978:

  Calc-Pi.pdf (Size: 2.54 MB / Downloads: 33)

Anyway, I am surprised that the author's original method of building up the equation to find the length of a side of the polygon does not work properly in my program. I have built a couple of more equations to compute the side length that work properly, but I remain confused why the original method used by the author of the article does not work properly.

Here's my code:

Code:

EXPORT CalcPi()
BEGIN
// Calculate Pi by inscribed ploygons
// Original author:
// George W. Ball, Alfred University

  R:=10;  // Use a circle of radius 10
  N:=4;
  S:=R*√(2);

  PRINT();
  PRINT("Machine value for Pi = " +(4*ATAN(1)));
  PRINT("Machine value for Pi = " +PI);
  PRINT(" ");
  PRINT("Sides      Perimiter");
  FOR K FROM 1 TO 28 DO
    PRINT(N +"      " +((S*N)/(2*R)));

//    Y:= S*S/4;
//    H=√(R*R-Y);
//    X:=R-H;
//    S:=√(X*X+Y);  // does not work

//    S:=√((R-(√(R*R-(S*S/4))))*(R-(√(R*R-S*S/4)))+(S*S/4));  // works

    S:=√((R-√(R*R-(S/2)^2))^2+(S/2)^2);  // works

    N:=2*N;
  END;
END;

Please take a look (if you want) and if there is something obvious that I'm missing, please let me know.

TIA,
smp