/* This program helps you make QQ plots, by generating the       */
/* quantiles from the desired theoretical distributions.         */
/* This version also brings in the empirical data for comparison. */
/* Written by Carey Williamson for CPSC 531 in November 2017     */

/* Usage: cc -o qq qq.c -lm                                      */
/*        qq                                                     */

#include <stdio.h>
#include <stdlib.h>
#include <math.h> /* use man 3 log for the math functions */

#define NUM_DATA_VALUES 1191
#define GRANULARITY 1.0/NUM_DATA_VALUES

#define A 10.0  /* left edge of Uniform distribution */
#define B 80.0  /* right edge of Uniform distribution */
#define P 0.1217 /* parameter of Geometric distribution */
#define MU 15.0 /* mean of Exponential distribution */
#define ALPHA 1.0 /* tail index of Pareto distribution */

#define MAX_DATA 10000

int main()
  {
    int i, num;
    float x, value;
    float datavalues[MAX_DATA];

    num = 0;
    while( scanf("%f\n", &value) > 0 )
      {
	datavalues[num] = value/1024.0;  /* convert to KB */
	datavalues[num] = value;
	num++;
      }
#ifdef DEBUG
    printf("That file had %d values\n", num);
#endif    
    
    x = 0.0;
    i = 0;
    while( x <= 1.0 )
      {
	value = A + floor((B-A+1)*x);    /* for EquiLikely(A,B) */
	value = x;    /* for Uniform(0,1) */
	value = A + (B-A)*x;    /* for Uniform(A,B) */
	value += 2.2;
	value = floor(log(1-x)/log(1-P));    /* for Geometric(P) */
	value = 1/pow((1-x), 1/ALPHA);    /* for Pareto(ALPHA) */
	value = -MU*log(1-x);    /* for Exponential(MU) */
	printf("%f %f ", value, x);  /* Theoretical model values */
	printf("%f %f", datavalues[i], 1.0*i/num);  /* Empirical data values */
	printf("\n");
	x += GRANULARITY;
	i++;
      }
  }