3/4 = 0 ???

[DARREN MATTHEW SCHREIBER]

I am trying to debug this simple method from a Schelling model.  The
function is to look at its neighbors, see their color, and report the
fraction of neighbors that are of a different color.  The result of the
internal print statements look correct except that the math is wrong.

Fraction is defined as Others/Neighbors, but if it outputs others=3 and
neighbors=4 then fraction comes out as 0... why?

Any number divided by itself gives one, but any other division results in
0.000.  This just doesn't make any sense to me and I am wondering if there
is something about float that I need to know?

        Darren



-(float)getFractionOf: (int) otherColor {
        float fraction=0.0;
        int xvals[4]={0,0,1,-1};
        int yvals[4]={-1,1,0,0};
        int i,j;
        int numNeighbors=0; //added for Version 2.5
        int numOthers=0;    //added for Version 2.5
        Person * neighbor;

        if(myType==1) 
          {
            // This enforces a VonNeuman neighborhood
            
            for(i=0;i<4;i++)
              {
                //printf(" %d : %d, %d ",i, myX+xvals[i], myY+yvals[i]);
                if ((((myX + xvals[i]) < worldSize) && ((myX + xvals[i])
>=0)) 
                    &&   (((myY + yvals[i]) < worldSize) && ((myY +
yvals[i]) >= 0)))
                  //keeps us on a 2d grid
                  {
                    numNeighbors=numNeighbors + 1;
                    if ((neighbor=[myWorld getObjectAtX: myX + xvals[i] Y:
myY+yvals[i]]))
                      if ([neighbor getColor]==otherColor)
                        numOthers=numOthers+1;
                  }  
                printf("X %d , Y %d ",myX, myY);
                printf("Others %d/Neighbors%d    ", numOthers,
numNeighbors);
                if (numNeighbors != 0)
                  fraction=(numOthers/numNeighbors);
                else
                  fraction=100.0;  // This is a warning flag for division
by zero
                printf("Fraction   %3.3f \n", fraction);
              }
          } 
        else
          {
          // This enforces a Moore neighborhood
            printf("Moore");
            for(i=-1;i<2;i++) 
              for(j=-1;j<2;j++) 
                if (((myX+xvals[i]<worldSize) && (myY+yvals[i]<worldSize)) 
                    && (!(myX+xvals[i]<0) && !(myY+yvals[i]<0))) //keeps
us on a 2d grid
                  {
                    numNeighbors=numNeighbors + 1;
                    if ((neighbor=[myWorld getObjectAtX: myX + xvals[i] Y:
myY+yvals[i]]))
                      if ([neighbor getColor]==otherColor)
                        numOthers=numOthers+1;
                  }
          }
     
       
        return fraction;
}



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