graph_unit.c

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#define NUM_LINE 10	
float arrayIndex[NUM_LINE];

int getArrayIndex(float min, float max, float unit) {
	float tmp, grp_unit;
	float grp_min, grp_max;
	
	tmp = (max - min) / (NUM_LINE - 1);
	grp_unit = unit;
	if (tmp > unit) {
		//ceil return smallest integer value greater than or equal param
		grp_unit = ceil(tmp / unit) * unit;
	}
	
	//Caculating unit for graph
	grp_min = 0;
	grp_min = max - (NUM_LINE - 1) * grp_unit;
	
	if (grp_min != min) {
		tmp = (grp_min + min) / 2;
		grp_min = (int)(tmp / unit) * unit;
	}
	int i;
	for (i = 0; i < NUM_LINE; i++) {
		arrayIndex[i] = grp_min + i * grp_unit;
	}
	return 0;
}

int main(int argc, char *argv[]) {
  int i, r;
  float min, max, unit;
  if (argc != 4) {
	return -1;
  }
  min = atof(argv[1]);
  max = atof(argv[2]);
  unit = atof(argv[3]);

  if (min < 0 || max < 0 || unit < 0 || min > max) {
	return -1;
  }
  //printf("min: %3.1f max: %3.1f unit: %3.1f\n", min, max, unit);

  r = getArrayIndex(min, max, unit);
  if (r == -1) {
  	return -1;
  }
  
  for (i = 0; i < NUM_LINE; i++) {
	printf("Num %d: %3.1f\n", i, arrayIndex[i]);
  }
  return 0;
}