Some useful matrix methods...

Every time while developing iOS Applications which use matrix related calculations, I used to think how to convert index to matrix co-ordinate etc. So i thought of writing this one -  why to reinvent the wheel every-time :)

-(NSInteger) getIndexFromMatrix : (CGPoint) inPoint size:(CGSize)gridSize

{

    if( (inPoint.x >= 0 && inPoint.x < gridSize.width) && (inPoint.y >= 0 && inPoint.y < gridSize.height))

        return inPoint.x*(gridSize.width-1) + (inPoint.x+inPoint.y);

    return -1;

}

-(CGPoint) getMatrixFromIndex : (NSInteger) index size:(CGSize)gridSize

{

    return CGPointMake(index/(int)gridSize.width, index%(int)gridSize.height);

}

-(BOOL) isIndexIsDialognal:(CGPoint)index1 andIndex:(CGPoint)index2

{

    return (abs(index1.x - index2.x)==abs(index1.y - index2.y));

}

-(NSMutableArray*) adjacentIndicesForIndex:(CGPoint)inPoint matrixSize:(CGSize) matrixSize

{

    NSMutableArray *array = [NSMutableArray array];

    

    for (int dx = -1; dx <= 1; ++dx) 

        for (int dy = -1; dy <= 1; ++dy) 

            if (dx != 0 || dy != 0) 

            {

                CGPoint adjacentIndex = CGPointMake(inPoint.x + dx, inPoint.y + dy);

                if(![self isIndexIsDialognal:adjacentIndex andIndex:inPoint]) //Checking for diagonal elements

                {

                    NSInteger index = [self getIndexFromMatrix:adjacentIndex size:matrixSize];

                    if(index >= 0)

                        [array addObject:[NSNumber numberWithInt:index]];

                }

            }

    return array;

}