Combinations problem C++

[ZeroVash]

So i supposed this is for a side project. I stumbled myself upon this fun/boring problem. And this being a C++ thread and in order to raise some discussion across the boards i'll post what i was doing (instead of just wasting time doing it myself xD )

So yeah the problem is pretty simple:

You'll have 3 variables. We can call them A,B and C for the moment. Their purpose is to be sent as function parameters to plot a control systems feedback output.(Not relevant for the time)

So what is the problem after all?

Each variable can take 4 forms: i) Either a small positive number (lets say 5) , ii) A small negative number (f.ex: -5), iii) A giant negative number (f.ex: -1000) and iv) A giant positive number (f.ex: 1000). You'll have to go trough every single possibility and send it trough to be plotted. Boring i know. But optimizing it for fast performances shall be fun  

I have a function handle called plot which basically sends the variables A,B,C and plots the current control system i'm looking at. 

So a basic algorithm for it would be:

A=5;
B=5;
C=5;
plot_C(A,B,C);
C=1000;
plot_C(A,B,C);
B=100;
C=5;
plot_C(A,B,C);
.

The plot handle can change like if you wanna work with pointers or something like that ^_^ Or try and work with arrays but i doubt that would be the best approach :> 

Can't wait to hear your responses guys  

[matheuslps]

I do not think if I understand well, but my first shot is something like (obvius one):

for (a=-1000;a<=1000;a++)
{
   for (b=-1000;b<=1000;b++)
   {
      for (c=-1000;c<=1000;c++)
      {
         plot_C(A,B,C);
      }
   }
}

With this way, I cover all possibilities. But do not think if it is fast....

bye

[ZeroVash]

Ahah you misunderstood

The variables can only take fixed values. So A,B,C can only be either -1000,-5,5,1000 .

[matheuslps]

Well, I know a bit of programming, but do not know how to to it in a fast way. You said that work with arrays is not the best aproach. Why?

a = [-1000,-5,5,1000]
b = [-1000,-5,5,1000]
c = [-1000,-5,5,1000]

for (i=0;i<4;i++)
{
  for (j=0;j<4;j++)
  {
     for (k=0;k<4;k++)
     {
        plot_C(A[i],B[j],C[k]);
     }
  }
}

bye

[alpha]

Hi,

I would really like to help you but i don't understand what are you trying to accomplish? (not a much difference, but you try to do this in C or C++)