8-14.cpp

能判断二次函数是否有根

/*3208006411*/
#include<stdio.h>
#define N 10
#define M 5
float score[N][M];
float a_stu[N],a_cour[M];
int r,c;
void main()
{int i,j;
float h;
float s_var(void);
float highest();
void input_stu(void);
void aver_stu(void);
void aver_cour(void);
input_stu();
aver_stu();
aver_cour();
printf("\n NO.     cour1   cour2    cour3    cour4    cour5  aver\n");
for(i=0;i<N;i++)
  {printf("No. %2d",i+1);
  for(j=0;j<M;j++)
    printf("%8.2f",score[i][j]);
    printf("%8.2\n",a_stu[i]);
    }
printf("\naverage:");
for(j=0;j<M;j++)
  printf("%8.2f\n",a_cour[j]);
  printf("\n");
  h=highest();
  printf("high:%7.2f    No. %2d  course %2d\n",h,r,c);
printf("variance %8.2f\n",s_var());
}
void input_stu(void)
{int i,j;
for(i=0;i<N;i++)
{printf("\ninput score of students %2d:\n",i+1);
for(j=0;j<N;j++)
  scanf("%f",&score[i][j]);
  }}
void aver_stu(void)
{int i,j;
float s;
for(i=0;i<N;i++)
 {for(j=0,s=0;j<M;j++)
  s+=score[i][j];
  a_stu[i]=s/5.0;
  }
  }
void aver_cour(void)
{int i,j;
float s;
for(j=0;j<M;j++)
{s=0;
for(i=0;i<N;i++)
 s+=score[i][j];
 a_cour[j]=s/(float)N;
 }}
float highest()
{float high;
int i,j;
high=score[0][0];
for(i=0;i<N;i++)
  for(j=0;j<M;j++)
    if(score[i][j]>high)
    {high=score[i][j];
     r=i+1;
     c=j+1;
     }
    return(high);
    }
float s_var(void)
{int i,j;
{int i;
float sumx,sumxn;
sumx=0.0;
sumxn=0.0;
for(i=0;i<N;i++)
   {sumx+=a_stu[i]*a_stu[i];
   sumxn+=a_stu[i];
   }
   return(sumx/N-(sumxn/N)*(sumxn/N));
   }
   }