evaluate data in a matrix in a spiral motion?

[DrJones]

I trying to evaluate data in a matrix in a spiral motion, but is having a hard time, figuring out how to make it move in that motion.

any suggestion?

[Krisando]

I once asked my math tutor this, he gave me a formula which calculates the x and y position from a single incrementing value.. If only I remembered what it was.

[DrJones]

I actually kinda have an idea which involves 4 states, each states increment in different direction.

so something like this pseudo---

int increment = 1;
state = 1;

switch (state)
 case 1: 
      for(int i = 0; i<= increment;i++)
{
  cout << matrix[m-i][n] << endl;

}

state = 2;
break;

case 2 :
      for(int i = 0; i<= increment;i++)
{
  cout << matrix[m][n+i] << endl;

}
increment++;
state = 3;

case 3:

      for(int i = 0; i<= increment;i++)
{
  cout << matrix[m+i][n] << endl;

}
state = 4;

case 4:
      for(int i = 0; i<= increment;i++)
{
  cout << matrix[m][n-i] << endl;

}
increment++;
state = 1;

would it work ?

[keskiverto]

Top row: x
Bottom row: x+h
Left column: y
Right column: y+k

Let say that you are in the upper left corner. [x][y]
You proceed right over all columns to the upper right corner. [x][y+k]
Top row: x+1
Then you go down to lower right corner, from [x+1][y+k] to [x+h][y+k]
Right column: y+k-1
Leftwards to lower left, from [x+h][y+k-1] to [x+h][y]
Bottom row: x+h-1
Upwards, from [x+h-1][y] to [x+1][y].
Left column: y+1

Notice how after completion of whole edge, the range was reduced by one?
How after completion of a circle the upper left corner is now at [x+1][y+1]?
That you can repeat the circle, until you are done?

Oh wait, was it from center or to center?

[DrJones]

Your start point will always be seen as center point for the spiral motion.


like this
http://i41.tinypic.com/24dmseu.png