数値計算法レポート1 - 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 main(){
  double avg,stddev,temp,sum,sumsq,cnt;
  FILE *fpdata1, *fpdata2;
 
  if( ( fpdata1 = fopen("temp.dat","rb")) == NULL){
    printf("error:cannot open temp.dat \n");
    exit(1);
  }
 
  if( ( fpdata2 = fopen("report.txt","w")) == NULL){
    printf("error:cannot open file \n");      
    exit(2);
  }
 
  sum=0;
  sumsq=0;
 
  for(cnt=0; ;cnt++){
    fscanf(fpdata1,"%lf",&temp);
    printf("input %lf\n",temp);
    if(temp==0.){
      printf("\n done! \n");
      break;
    }
      sum = sum + temp;
      sumsq = sumsq + pow(temp,2);
      printf("sum = %lf\n",sum);      
  }
 
  avg=sum/cnt;
  stddev=sqrt((sumsq-cnt*pow(avg,2))/(cnt-1));
 
  fprintf(stderr,"cnt = %.0lf\naverage = %.1lf\nstandard deviation = %.1lf\n",cnt,avg,stddev);
  fprintf(fpdata2,"average = %.1lf\nstandard deviation = %.1lf\n",avg,stddev);
  fclose(fpdata1);
  fclose(fpdata2);
}