MPSCNNPoolingL2NormGradient(3)				 MetalPerformanceShaders.framework			    MPSCNNPoolingL2NormGradient(3)

NAME

       MPSCNNPoolingL2NormGradient

SYNOPSIS

       #import <MPSCNNPooling.h>

       Inherits MPSCNNPoolingGradient.

   Instance Methods
       (nonnull instancetype) - initWithDevice:kernelWidth:kernelHeight:strideInPixelsX:strideInPixelsY:
       (nullable instancetype) - initWithCoder:device:

   Additional Inherited Members
Detailed Description
       This depends on Metal.framework	Specifies the filter for computing the gradient of the L2-Norm pooling filter. The operation
       backpropagates a gradient vector using chain rule.

       L2-Norm pooling forward pass is defined as:

       out(x) = sqrt( sum_{dx in Window(x)} in(s*x+dx) * in(s*x+dx) ), where

       the pooling window definition 'Window(x)' follows MPSCNNPooling specification and 's' is the pixel stride and in() is the source input
       image.

       Hence the partial derivative of the output value wrt. to the input value needed in the gradient backpropagation in MPSCNNPoolingGradient
       is:

       d out(x)/d in(y) = sum_{dx in Window(x)} delta_{s*x+dx, y} in(s*x+dx) / out(x), where

       delta_{x,y} is the Kronecker delta symbol for which

       delta_{x,y} =  {  1, when x == y
		      {  0, otherwise,

	and out(x) is the L2-norm pooling value at point 'x' defined above.

Method Documentation
   - (nullable instancetype) initWithCoder: (NSCoder *__nonnull) aDecoder(nonnull id< MTLDevice >) device
       NSSecureCoding compatability  See MPSKernel::initWithCoder.

       Parameters:
	   aDecoder The NSCoder subclass with your serialized MPSCNNPoolingL2NormGradient
	   device The MTLDevice on which to make the MPSCNNPoolingL2NormGradient

       Returns:
	   A new MPSCNNPoolingL2NormGradient object, or nil if failure.

       Reimplemented from MPSCNNPoolingGradient.

   - (nonnull instancetype) initWithDevice: (nonnull id< MTLDevice >) device(NSUInteger) kernelWidth(NSUInteger) kernelHeight(NSUInteger)
       strideInPixelsX(NSUInteger) strideInPixelsY
       Initialize a gradient L2-norm pooling filter

       Parameters:
	   device The device the filter will run on
	   kernelWidth The width of the kernel. Can be an odd or even value.
	   kernelHeight The height of the kernel. Can be an odd or even value.
	   strideInPixelsX The input stride (upsampling factor) in the x dimension.
	   strideInPixelsY The input stride (upsampling factor) in the y dimension.

       Returns:
	   A valid MPSCNNPoolingL2NormGradient object or nil, if failure.

       Reimplemented from MPSCNNPoolingGradient.

Author
       Generated automatically by Doxygen for MetalPerformanceShaders.framework from the source code.

Version MetalPerformanceShaders-100				  Thu Feb 8 2018				    MPSCNNPoolingL2NormGradient(3)