CODEWITHSUNDEEP
crecursionseriesiteration
David_Maendlen
David_Maendlen

Reputation: 35

Language: C; Compute a series recursive and iterative

I am currently trying to prepare myself for an exam and I stumbled across the following assignment:

Compute the series (recursive and iterative) 1-(1/2)+(1/3)-(1/4)+(1/5)...(1/n). I searched the web in general and this page in particular but unfortunately I only found java-based solutions I didn't understand.

So, please help me :)

My best effort so far only gets me the answer "1.00" :-/

Here is what I did (in full):

#include <stdio.h>

float reihe_ite(int n); 
float reihe_rek(int n); 

int main(){
        float a,b;
        a=reihe_ite(5);
        b=reihe_rek(5);

        printf("\niterativ: %.2f\nrekursiv: %.2f", a, b); 

        return 0;
}

float reihe_ite(int n){ 
        int i;
        float x=0;
        for(i=1;i<=n;i++){
                if(i%2==0){
                        x=x-(1/i);
                }   
                else{
                        x=x+(1/i);
                }   
        }   
        return x;
}

float reihe_rek(int n){ 
        if(n==1)
                return 1;
        else{
                if(n%2==0){
                        return reihe_rek(n-1)-(1/n);
                }    

                else{
                        return reihe_rek(n-1)+(1/n);
                }   

        }   
}

Upvotes: 0

Views: 110

Answers (1)

ouah
ouah

Reputation: 145829

x=x-(1/i);

1/i is an integer division.

Use:

   x=x-(1.0f/i);

for a float division

Upvotes: 2

Related Questions