anchor.diff:      % reset to begining of next row
       NewRowData = [],                                 % reset data for row to empty
       NewXPix    = Width,                              % reset to end of line
  -    NewXR      = maps:get(xRealRight,ConfigMap),     % reset to end of line
  +    NewXR      = maps:get(xRealRight, ConfigMap),     % reset to end of line
       NewYPix    = YPix - 1,                           % increment row
       NewYI      = YI - DeltaY,                          % increment row
       computeFractalData( NewRows, NewRowData,
                      NewXPix, NewXR, DeltaX, Width,
  -                   NewYPix, NewYI, DeltaY,Height,
  +                   NewYPix, NewYI, DeltaY, Height,
                      ConfigMap);
   
   computeFractalData( Rows, RowData,       % row data computed so far
  
positive.code:     NewXR      = XR - DeltaX,                        % decrease XR to the left
      computeFractalDataIntoFile( DataFile, NewRowData,
                     NewXPix, NewXR, DeltaX, Width,
                     YPix, YI, DeltaY,Height,
                     ConfigMap).
  
  %%%%%%%%%%%%%%%%%%%%%
  
negative.code: %%%%%%%%
  computeFractalDataIntoFile(ConfigMap) ->
      %% get config needed
      DataFileName  = maps:get(dataFileName, ConfigMap),
      %% create height rows of width columns of pixels
      Width           = maps:get(width, ConfigMap),
      Height          = maps:get(height, ConfigMap),
      %% each pixel has a corresonding complex number defined by corners of the box
      XRealRight      = maps:get(xRealRight, ConfigMap),
      XRealLeft       = maps:get(xRealLeft, ConfigMap),
      YImaginaryLow   = maps:get(yImaginaryLow, ConfigMap),
      YImaginaryHigh  = maps:get(yImaginaryHigh, ConfigMap),
      %% box is bounded on left by x > XRealLeft and bounded on right by x < XRealRight
      %% box is bounded on top by y > YImaginaryHigh and bounded on bottom by y > YImaginaryLow
      %% box is width pixels wide and height pixels high
  