提交 2289c141 编写于 作者: L liuyuan 提交者: qingqing01

Refine comment for CRF related headers. (#117)

上级 332194c8
...@@ -25,7 +25,7 @@ namespace paddle { ...@@ -25,7 +25,7 @@ namespace paddle {
/** /**
* A layer for calculating the cost of sequential conditional random field * A layer for calculating the cost of sequential conditional random field
* model. * model.
* See LinearChainCRF.h for the detail of the CRF formulation. * See class LinearChainCRF for the detail of the CRF formulation.
*/ */
class CRFLayer : public Layer { class CRFLayer : public Layer {
public: public:
......
...@@ -21,39 +21,39 @@ namespace paddle { ...@@ -21,39 +21,39 @@ namespace paddle {
class LinearChainCRF { class LinearChainCRF {
public: public:
/* /**
The size of para and grad must be (numClasses + 2) * numClasses. * The size of para and grad must be \f$(numClasses + 2) * numClasses\f$.
The first numClasses values of para are for starting weights (a). * The first numClasses values of para are for starting weights (\f$a\f$).
The next numClasses values of para are for ending weights (b), * The next numClasses values of para are for ending weights (\f$b\f$),
The remaning values are for transition weights (w). * The remaning values are for transition weights (\f$w\f$).
*
The probability of a state sequence s of length L is defined as: * The probability of a state sequence s of length \f$L\f$ is defined as:
P(s) = (1/Z) exp(a_{s_1} + b_{s_L} * \f$P(s) = (1/Z) exp(a_{s_1} + b_{s_L}
+ \sum_{l=1}^L x_{s_l} * + \sum_{l=1}^L x_{s_l}
+ \sum_{l=2}^L w_{s_{l-1},s_l}) * + \sum_{l=2}^L w_{s_{l-1},s_l})\f$
where Z is a normalization value so that the sum of P(s) over all possible * where \f$Z\f$ is a normalization value so that the sum of \f$P(s)\f$ over all possible
sequences is 1, and x is the input feature to the CRF. * sequences is \f$1\f$, and \f$x\f$ is the input feature to the CRF.
*/ */
LinearChainCRF(int numClasses, real* para, real* grad); LinearChainCRF(int numClasses, real* para, real* grad);
/* /**
Calculate the negative log likelihood of s given x. * Calculate the negative log likelihood of s given x.
The size of x must be length * numClasses. Each consecutive numClasses * The size of x must be length * numClasses. Each consecutive numClasses
values are the features for one time step. * values are the features for one time step.
*/ */
real forward(real* x, int* s, int length); real forward(real* x, int* s, int length);
/* /**
Calculate the gradient with respect to x, a, b, and w. * Calculate the gradient with respect to x, a, b, and w.
The gradient of x will be stored in dx. * The gradient of x will be stored in dx.
backward() can only be called after a corresponding call to forward() with * backward() can only be called after a corresponding call to forward() with
the same x, s and length. * the same x, s and length.
NOTE: The gradient is added to dx and grad (provided at constructor). * @note The gradient is added to dx and grad (provided at constructor).
*/ */
void backward(real* x, real* dx, int* s, int length); void backward(real* x, real* dx, int* s, int length);
/* /**
Find the most probable sequence given x. The result will be stored in s. * Find the most probable sequence given x. The result will be stored in s.
*/ */
void decode(real* x, int* s, int length); void decode(real* x, int* s, int length);
......
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