zetwhite/cuda-practice

repo for cuda practice code.

cuda-practice's Issues

EX3-5

• 5. Consider a 3D tensor with a width of 400, a height of 500, and a depth of 300. The tensor is stored as a one-dimensional array in row-major order. Specify the array index of the tensor element at x = 10, y = 20, and z = 5.

Assumption

• width corresponds to Y axis
• height corresponds to Z axis
• channel corresponds to X axis

			 channel(depth) 
		  / 
	    / 
	  /
  	* - - - - > width(row)
  	|
  	| 
  	|
	height(column) 

		  X  
	    / 
	  /
  	* - - - Y
  	|
	| 
	Z 

Solve

• row-major order means that
  • the elements are continuous in row(width) direction.
  • traverse row(width) direction first, then traverse column direction next and traverse channel direction lastly
  • sometime, called CHW layout

channel_stride * (x-1) +  height_stride * (z-1) + row_stride * (y-1) 
= 400 * 500 * (10-1) + 400 * (5 - 1)  + 1 * 19 
= 1800000 + 1600 + 19 
= 1801618