这是今天上课遇到的一个程序，有些东西不大了解。。。。

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

double factorial(int);
double Term(double, int);

int main()
{    int I;
     double dTemp, dEps, dx, dSin;


     printf("Please enter a value of x:");
     scanf("%lf",&dEps);
     printf("Enter the accuracy value: ");
     scanf("%lf",&dx);
     
     while (dEps<=0)
          {
              printf("Input wrong! Enter Eps:");
              scanf("%lf",&dEps);
           }

     printf("The Sin(x) is: %lf\n",sin(dx));

     I=1;
     dTemp =Term(dx, I);
     dSin=0;

     while(fabs(dTemp)>=dEps)
          {
              Sin=dSin+dTemp;
              I=I+1;
              dTemp=Term(x,I);
           }

     printf("Sin x is: %lf\n",Sin);

     if(fabs(dTemp)<dEps)
         printf("Looping stop at Term(%d) = %lf",I,dTemp);

     printf("\n");

     return 0;
}


double Factorial(int J)
{
       int Z;
       double Fac=1;

       for(Z=1; Z<=J; Z++)
          {
              Fac=Fac*Z;
           }
       return (Fac);
}

double Term(double dx, int I)
{
       int J=(2*I)-1;
       double dTemp;
       dTemp = (pow(dx,J))/Factorial(J);
       if ((I%2)==0)
           dTemp=-1*dTemp;
       printf("I=%d J=%d Temp=%lf\n",I,J,dTemp);

       return(dTemp);
}


1.在内int main之前的两个定义double factorial(int);   double Term(double, int);是啥意思？

2.scanf("%lf",&dEps);中%后面的l是什么意思？

3.if(fabs(dTemp)<dEps)这个条件中的fabs指的什么？

4.double Factorial(int J)和double Term(double dx, int I)定义是什么意思？

希望前辈能解释一下。。。谢谢

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