loss.lisp

(in-package #:lispnet)


(defun clip (x minx maxx)
  (lazy #'* -1.0 (lazy #'max (* -1 maxx) (lazy #'* -1.0 (lazy #'max minx x)))))


(defun mse (y-true y-pred)  (lazy #'/ (lazy-allreduce #'+ (lazy #'expt (lazy #'- y-pred y-true) 2))
                                  (coerce (shape-size (lazy-array-shape y-pred)) *network-precision* )))

;; this loss fucntion can be used to create a custom loss fucntion in the forward pass.
(defun output-loss(y-true y-pred) y-pred)

(defun mae (y-true y-pred)  (lazy #'/ (lazy-allreduce #'+ (lazy #'abs (lazy #'- y-pred y-true) ))
                                  (coerce (shape-size (lazy-array-shape y-pred)) *network-precision* )))

(defun binary-cross-entropy (y-true y-pred)
  (let ((y-pred-stable (clip y-pred 0.0000001 0.9999999)))
    (lazy #'* -1.0 (lazy #'/  (lazy-allreduce #'+ (lazy #'+ (lazy #'* y-true (lazy #'log y-pred-stable))
                                                        (lazy #'* (lazy #'- 1.0 y-true) (lazy #'log (lazy #'- 1.0 y-pred-stable)))))
                         (coerce (shape-size (lazy-array-shape y-pred)) *network-precision* )))))


(defun categorial-cross-entropy (y-true y-pred)
  (let* ((batch-size (first(shape-dimensions(lazy-array-shape y-true))))
         (y-pred-stable (clip y-pred 0.0000001 0.9999999)))
    (lazy #'* -1.0 (lazy #'/  (lazy-allreduce #'+ (lazy #'* y-true (lazy #'log y-pred-stable)))                                                      
                         (coerce batch-size *network-precision*)))))
						 

(defun binary-accuracy (y-true y-pred)
  (let ((binary-pred (binary-decision y-pred 0.5)))
    (lazy #'/ 
	  (lazy-allreduce #'+ (lazy #'+ (lazy #'* (lazy #'- 1.0 binary-pred) (lazy #'- 1.0 y-true)) (lazy #'* binary-pred y-true)))
          (coerce (shape-size (lazy-array-shape y-true)) *network-precision* ))))

(defun categorial-accuracy (y-true y-pred)
  (let* ((batch-size (first(shape-dimensions(lazy-array-shape y-true))))
         (sample-shape (~l (mapcar #'range (cdr(shape-dimensions(lazy-array-shape y-true))))))
         (argmax-pred (lazy-batch-argmax y-pred)))
		
    (lazy #'/ (lazy-allreduce #'+ (lazy #'* y-true argmax-pred)) (coerce batch-size *network-precision*))))