数値計算法レポート課題１（OK） - 阪大理学部科学計算・開発サークル -Circle for Science Caluculation and Development-

#include<stdio.h>
#include<stdlib.h>
#include<math.h>
 
int i;
double data,sum,mean,mean2,meansq,stdev,sum2,status;
FILE *fpDATA;
 
int main(){
 
  fpDATA = fopen("input.dat","r");
 
  if(fpDATA==NULL){
    printf("input file open error !\n");
    printf("program terminated.\n");	
    exit(0);
  }	
 
  i=0;
  sum=0;
  sum2=0;
  status = 0;
  data=0;
 
 
  while(fscanf(fpDATA, "%lf", &data) != EOF){
    sum = sum + data;
    sum2 = sum2 + data * data;
    i++;
  }
 
  mean = sum/i;
  mean2 = sum2/i;
  meansq = mean * mean ;
  stdev = sqrt(mean2 - meansq);
 
  printf("Number of data = %d\n",i);
  printf("Mean = %lf\n",mean);
  printf("Standard Deviation = %lf\n",stdev);
 
  fclose(fpDATA);		
 
}
  i=0;
  sum=0;
  sum2=0;
  status = 0;
 
  while(status != EOF){
    status = fscanf(fpDATA, "%lf", &data);
    sum = sum + data;
    sum2 = sum2 + data * data;
    i++;
  } 
 
  mean = sum/(i-1);
  mean2 = sum2/(i-1);
  meansq = mean * mean ;
  stdev = sqrt(meansq - mean2);
 
  printf("Number of data = %d\n",i-1);
  printf("Mean = %lf\n",mean);
  printf("Standard Deviation = %lf\n",stdev);
 
  fclose(fpDATA);		
 
}