function problem

[Agusta06]

Greetings,

I’m trying to write a function to compute and return the following value for integer x.


f(x) =
x + 2 if x < 0
0 if x = 0
1 + 2 + ... + x if x > 0


Can anyone help me set it up?

[arne]

Greetings,

I’m trying to write a function to compute and return the following value for integer x.


f(x) =
x + 2 if x < 0
0 if x = 0
1 + 2 + ... + x if x > 0


Can anyone help me set it up?

Sure. Why don't you post what you have so far? This could be used as a starting point, and it would be much more instructive for you than if someone else does your assignment ;-)

[emaghero]

The following implementation should solve your problem

#include <cstdlib>
#include <iostream>

using namespace std;

double f(double x);

int main(int argc, char *argv[])
{
double z;
cout<<"Enter a value for z\n";
cin>>z;
cout<<f(z)<<endl;

system("PAUSE");
return EXIT_SUCCESS;
}
double f(double x)
{
if(x>0){
double sum=0;
for(int i=1;i<=(int)(x);i++){
sum+=i;
}
return sum;
}
else if(x==0){
return 0;
}
else{
return x+2;
}
}

If you are looking for an excellent( and cheap) book on numerical computing I highly reccomend
"Introducing C++ for Scientist's, Engineers and Mathematicians"
by Derek Capper

It is really an excellent book. I use it all the time. It costs roughly €30 on amazon.co.uk. Well worth it.

emaghero

[Agusta06]

Thanxs for the aid and the tip. i'm ordering a copy from amazon this week.

Just one more question. how would I be able to make the program loop so that it allows me to repeatedly test the function during the output instead of running it over and over each time for different values of Z?

regards