# pls check it for me

Discussion in 'C' started by vipul15singh, Mar 6, 2010.

1. ### vipul15singhNew Member

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there is a exponential program, it has some problem in result {if x=1 and n=5 the answer must be 2.7016}
pls tell me the problem and solution also

Code:
```#include<stdio.h>
#include<conio.h>
float expo(float,float,int,float);
float term(float,float,float);
main()
{
int n;
float e=0.0,t=1.0,x;
static float s=1.0;
clrscr();
printf("\nenter variable & no ofterms:=");
scanf("%f%d",&x,&n);
e=expo(x,t,n,s);
printf("\nsum=%f",e);
getch();
return;
}
float expo(float x,float t,int n,float s)
{
float c=1.0,e=0;
if(t<n)
{
e=term(x,t,c);
s=s+e;
expo(x,t+1.0,n,s);
}
return(s);
}
float term(float x,float t,float c)
{
if(t>=1)
{
c=c*(x/t);
term(x,t-1,c);
}
return(c);
}```

Last edited by a moderator: Mar 6, 2010
2. ### virxenNew Member

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check the result again.i think it must be 2.7083

i made 2 corrections and also i changed how scanf gets its data.

Code:
```#include<stdio.h>
#include<conio.h>
float expo(float,float,int,float);
float term(float,float,float);
int main()
{
int n;
float e=0.0,t=1.0,x;
static float s=1.0;
//clrscr();
[COLOR="Red"]printf("\nenter variable:");
scanf("%f",&x);
printf("\nenter no of terms:");
scanf("%d",&n);[/COLOR]
e=expo(x,t,n,s);
printf("\nsum=%f",e);
getch();
return 0;
}
float expo(float x,float t,int n,float s){
float c=1.0,e=0;
if(t<n){
e=term(x,t,c);
s=s+e;
t++;
[COLOR=Red]s=expo(x,t,n,s);[/COLOR]
}
return(s);
}
float term(float x,float t,float c)
{
if(t>=1){
c=c*(x/t);
[COLOR=Red]c=term(x,t-1,c);[/COLOR]
}
return(c);
}

```

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3. ### vipul15singhNew Member

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thanks virxen, i m very happy to get sol.,pls tell me whats the actual problem in prog at (vipul.fifteen@yahoo.com)
once again thanks

4. ### virxenNew Member

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a better solution is this

Code:
```#include<stdio.h>
#include<conio.h>
float expo(float,float,int,float);
float term(float,float,float);
int main()
{
int n;
float e=0.0,t=1.0,x;
static float s=1.0;
//clrscr();
printf("\nenter variable:");
scanf("%f",&x);
printf("\nenter no of terms:");
scanf("%d",&n);
e=expo(x,t,n,s);
printf("\nsum=%f",e);
getch();
return 0;
}
float expo(float x,float t,int n,float s){
float c=1.0,e=0;
if(t<n){
e=term(x,t,c);
s=s+e;
t++;
[COLOR=Red]return expo(x,t,n,s);[/COLOR]
}
return(s);
}
float term(float x,float t,float c)
{
if(t>=1){
c=c*(x/t);
[COLOR=Red]return term(x,t-1,c);[/COLOR]
}
return(c);
}

```

the error is that when you have a recursive function like above
you must keep a sequential line between its calls and not to break it.

for instance(each one calls its previous )

4!=3!*4=(2!*3)*4=( (1!*1*2)*3 )*4=((0!*1*2)*3)*4

without the return i added here you always return c as the result which is not
changing.

for more on this check this link
http://www.java2s.com/Tutorial/C/0160__Function/Recursion.htm