BIORHYTH.C

/* BIORHYTH.C by Michael J. Chappell  June 22, 2015
   A fairly direct port of BIORHYTHM.BAS Copyright 1979 
   by Phil Feldman and Tom Rugg.

   Source code compiles under MIX Power C.  Compiled 
   for FreeDOS and should work under MS-DOS or PC-DOS.
   Tested under DOSBox 0.73 on Mac OS X 10.8.5

   The code for dealing with the dates wasn't working as expected.  
   So I rewrote date2Julian and julian2Date.  I rewrote those sections 
   based on julian Day Calculations (Gregorian Calendar) at 
   http://quasar.as.utexas.edu/BillInfo/JulianDatesG.html .

   See source for notes.
*/
#include <stdio.h>
#include <math.h>
#include "trs81.h"

int l; /* counter of number of lines on screen */
int k; /* loop and work variable */

float t; /* num of chars on one side of the center of the chart */
float n; /* number of days between birth and current chart date */
float v; /* number of days in current biorhythm cycle (23, 28 or 33) */

float m; /* month */
float d; /* day */
float y; /* year (100 or greater) */

char c$[80]; /* string with date in month/day/year format */
char l$[80]; /* string with one line of the biorhythm chart */
char r$[80]; /* reply from operator after screen fills up */

char a$[80]; /* work variable */

float p; /* pi */
float jb; /* birth date in julian format */
float jd; /* julian date calculated in subroutine */
float jc; /* chart start date in julian format */
float w, b; /* work variables */
float r; /* remainder of n/v (number of days into cycle */

char temp[255];

int main(int argc, char **argv) {
  Initialize();
  l=0; t=25; p=3.1415926535;
  Cls();
  PrintTab(15);
  Print("BIORHYTHM\n");
  Print("\n");
  for (;;) {
    Print("\nEnter birth date");
    getDate();
    date2Julian();
    jb = jd;
    Print("\nEnter start date for chart");
    getDate();
    date2Julian();
    jc = jd;
    if (jc<jb) {
      Print("\nChart date can't be earlier than");
      Print("\nbirth date.  Try again.");
      continue;
    } else break;
  }
  do {
    header();
    do {
      n = jc-jb;
      v = 23; remainder(); plot();
      v = 28; remainder(); plot();
      v = 33; remainder(); plot();
      julian2Date();
      sprintf(temp,"%s%s\n", c$, l$);
      Print(temp);
      jc = jc+1;
      l++;
    } while (l<12);
    l = 0;
    Print("Press 'E' to end, SPACE to continue");
    do { r$[0]=Inkey$(); } while (!r$[0]);
  } while (r$[0]!='E' && r$[0]!='e');
/*
  sprintf(temp, "\nJulian Birth date: %f", jb);
  Print(temp);
  sprintf(temp, "\nJulian Chart date: %f", jc);
  Print(temp);
*/
  while (!Inkey$());
} /* main */

void Initialize(void) {
  InitializeTRS80(0);
  return;
} /* Initialize */

void getDate(void) {
/* sets m, d, and y (month, day, and year) */
char temp[255];

  do {
    Print("\nMonth (1 to 12)?");
    scanf(" %f", &m);
    poscurs(cursrow()-1, 0);
  } while ((m<1.0) || (m>12.0));
  do {
    Print("\nDay (1 to 31)?");
    scanf(" %f", &d);
    poscurs(cursrow()-1, 0);
  } while ((d<1.0) || (m>31.0));
  do {
    Print("\nYear?");
    scanf(" %f", &y);
    poscurs(cursrow()-1, 0);
  } while (y<0.0);
  if (y<100) {
    y+=1900;
    sprintf(temp, "\n%4.0f Assumed.", y);
    Print(temp);
  }
} /* getDate */

void date2Julian(void) {
/* sets jd based on m, d, y */
/* direct translation (hopefully)
  w = floor((m-14)/12);
  jd = floor(1461*(y+4800+w)/4);
  b = floor(367*(m-2-w*12)/12);
  jd = jd+b;
  b = floor(floor(3*(y+4900+w))/4);
  jd = jd+d-32075-b;
*/
/* replacement with trusted code 

1) Express the date as Y M D, where Y
   is the year, M is the month number (Jan = 1, Feb = 2, etc.), and D is
   the day in the month.

2) If the month is January or February, subtract 1 from the year to
   get a new Y, and add 12 to the month to get a new M. (Thus, we are
   thinking of January and February as being the 13th and 14th month of
   the previous year).

3) Dropping the fractional part of all results of all multiplications
   and divisions, let

  A = Y/100
  B = A/4
  C = 2-A+B
  E = 365.25x(Y+4716)
  F = 30.6001x(M+1)
  JD= C+D+E+F-1524.5

This is the Julian Day Number for the beginning of the date in
question at 0 hours, Greenwich time. Note that this always gives you a
half day extra. That is because the Julian Day begins at noon,
Greenwich time.

*/
    float A, B, C, E, F, JD, Y, M, D;
    Y=y;
    M=m;
    D=d;

    if (m<3) {
        M=m+12;
        Y=y-1;
    }
    A=floor(Y/100);
    B=floor(A/4);
    C=2-A+B;
    E=floor(365.25*(Y+4716));
    F=floor(30.6001*(M+1));
    JD=C+D+E+F-1524.5;
    jd=JD;
} /* date2Julian */

void julian2Date(void) {
/* sets c$ (and m, d, y) based on jc */
/* code not working as expected
  w=jc+68569;
  r=floor(4*w/146097);
  w=w-floor((146097*r*3)/4);
  y=floor(4000*(w+1)/1461001);
  w=w-floor(1461*y/4)+31;
  m=floor(80*y/2447);
  d=w-floor(2447*m/80);
  w=floor(m/11);
  m=m+2-12*w;
  y=100+(r-49)+y+w;
*/
/* replacement with trusted code

To convert a Julian Day Number to a Gregorian date, assume that it is
for 0 hours, Greenwich time (so that it ends in 0.5). Do the following
calculations, again dropping the fractional part of all multiplicatons
and divisions. Note: This method will not give dates accurately on the
Gregorian Proleptic Calendar, i.e., the calendar you get by extending
the Gregorian calendar backwards to years earlier than 1582. using the
Gregorian leap year rules. In particular, the method fails if
Y<400.

  Q = JD+0.5
  Z = Integer part of Q
  W = (Z - 1867216.25)/36524.25
  X = W/4
  A = Z+1+W-X
  B = A+1524
  C = (B-122.1)/365.25
  D = 365.25xC
  E = (B-D)/30.6001
  F = 30.6001xE
  Day of month = B-D-F+(Q-Z)
  Month = E-1 or E-13 (must get number less than or equal to 12)
  Year = C-4715 (if Month is January or February) or C-4716 (otherwise)

 */
    float Q, Z, W, X, A, B, C, D, E, F, JD;

    JD=jc;
    Q = JD+0.5;
    Z = floor(Q);
    W = floor((Z-1867216.25)/36524.25);
    X = floor(W/4);
    A = Z+1+W-X;
    B = A+1524;
    C = floor((B-122.1)/365.25);
    D = floor(365.25*C);
    E = floor((B-D)/30.6001);
    F = floor(30.6001*E);
    d = floor(B-D-F+(Q-Z));
    m = E-1;
    y = C-4716;
    if (m>12) {
        m = m-12;
        y = y+1;
    }
    
  sprintf(c$, "%02d/%02d/%02d", (int)m, (int)d, (int)y%100);
} /* julian2Date */

void remainder(void) {
/* sets r based on n/v */
  w = floor(n/v);
  r = n-(w*v);
} /* remainder */

void plot(void) {
/* plot a point on l$ based on v and r */
  if (v==23) {
    for (k=0; k<2*t+1; k++) l$[k]=' '; l$[k]='\0';
    l$[(int)t-1]=149;
  }
  if (v==23) c$[0]='P';
  else if (v==28) c$[0]='E';
  else c$[0]='I'; /* v==33 */
  w = 2*p*(r/v);
  w = t*sin(w)+t+0.5;
  w = floor(w);
  if (l$[(int)w]=='P' || l$[(int)w]=='E' || l$[(int)w]=='*') c$[0]='*';
  l$[(int)w] = c$[0];

} /* plot */

void header(void) {
/* clear screen and display headings */
  Cls();
  Print(
"                            BIORHYTHM\n");
  Print(
"--DATE--        D O W N         0           U P\n");
  PrintTab(8);
  for (k=0; k<2*t+1; k++)
    PrintChr(131);
  Print("\n");
} /* header */
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Friday, 18 July 2025 Michael J. Chappell Contact me at: mcsuper5@freeshell.org
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