sum=sum*i/(2*i+1)和sum*=i/(2*i+1)的区别

#include

#include

#include

doublefun(doubleeps)

{

doublet=1.0,sum=1.0;

inti=1;

while(sum>=eps)/*当某项大于精度

要求时,继续求下一项*/

{sum=sum*i/(2*i+1);/*求多

项式的每一项*/

t=t+sum;/*累加求和*/

i++;

}

return2*t;

}

voidmain()

{

doublex;

printf("Inputeps:");

scanf("%lf",&x);

printf("neps=%lf,PI=%lfn",

x,fun(x));

}

#include

#include

#include

doublefun(doubleeps)

{inti=1;

doublet=1.0,sum=0;

while(t>=eps)

{

sum+=t;

t*=i/(2*i+1);

++i;

}

return2*sum;

}

voidmain()

{

doublex;

printf("Inputeps:");

scanf("%lf",&x);

printf("neps=%lf,PI=%lfn",

x,fun(x));

}为什么结果不一样?