add implementation for sigmoid layer (not tested)

5 files changed, 64 insertions, 8 deletions

diff --git a/layer/affine.lua b/layer/affine.lua
index 221aacd..94e7497 100644
--- a/layer/affine.lua
+++ b/layer/affine.lua
@@ -11,6 +11,7 @@ function LinearTransParam:write(pfhandle)
 end
 
 function AffineLayer:__init(id, global_conf, ltp, bp)
+    self.id = id
     self.ltp = ltp
     self.bp = bp
     self.gconf = global_conf
diff --git a/layer/sigmoid.lua b/layer/sigmoid.lua
new file mode 100644
index 0000000..d69e9e3
--- /dev/null
+++ b/layer/sigmoid.lua
@@ -0,0 +1,14 @@
+local SigmoidLayer = nerv.class("nerv.SigmoidLayer", "nerv.Layer")
+
+function SigmoidLayer:__init(id, global_conf)
+    self.id = id
+    self.gconf = global_conf
+end
+
+function SigmoidLayer:propagate(input, output)
+    output:sigmoid(input)
+end
+
+function SigmoidLayer:back_propagate(next_bp_err, bp_err, input, output)
+    next_bp_err:sigmoid(bp_err, output)
+end
diff --git a/matrix/cukernel.h b/matrix/cukernel.h
index 3cad489..b2b6cb2 100644
--- a/matrix/cukernel.h
+++ b/matrix/cukernel.h
@@ -1,5 +1,6 @@
 #ifdef NERV_GENERIC_CUKERNEL
 void cudak_(cuda_sigmoid)(const Matrix *a, Matrix *b);
+void cudak_(cuda_sigmoid_grad)(const Matrix *output, const Matrix *err, Matrix *nerr);
 void cudak_(cuda_rowsum)(const Matrix *a, Matrix *b);
 void cudak_(cuda_rowmax)(const Matrix *a, Matrix *b);
 void cudak_(cuda_colsum)(const Matrix *a, Matrix *b);
diff --git a/matrix/generic/cukernel.cu b/matrix/generic/cukernel.cu
index 8b929e4..517393e 100644
--- a/matrix/generic/cukernel.cu
+++ b/matrix/generic/cukernel.cu
@@ -16,6 +16,18 @@ __global__ void cudak_(sigmoid)(const MATRIX_ELEM *a, MATRIX_ELEM *b,
     b[idx] = 1.0 / (1.0 + exp(-a[idx]));
 }
 
+__global__ void cudak_(sigmoid_grad)(const MATRIX_ELEM *output,
+                                    const MATRIX_ELEM *err,
+                                    MATRIX_ELEM *nerr,
+                                    int nrow, int ncol, int stride) {
+    int j = blockIdx.x * blockDim.x + threadIdx.x;
+    int i = blockIdx.y * blockDim.y + threadIdx.y;
+    long idx;
+    if (i >= nrow || j >= ncol) return;
+    idx = j + i * stride;
+    nerr[idx] = output[idx] * (1.0 - output[idx]) * err[idx];
+}
+
 __global__ void cudak_(softmax_final)(const MATRIX_ELEM *a, MATRIX_ELEM *b,
                         const MATRIX_ELEM *max, const MATRIX_ELEM *deno,
                         int nrow, int ncol, int stride, int mstride) {
@@ -134,6 +146,19 @@ extern "C" {
             b->stride / sizeof(MATRIX_ELEM));
     }
 
+    void cudak_(cuda_sigmoid_grad)(const Matrix *output,
+                                    const Matrix *err, Matrix *nerr) {
+        dim3 threadsPerBlock(CUDA_THREADS_N,
+                CUDA_THREADS_N);
+        dim3 numBlocks(CEIL_DIV(nerr->ncol, threadsPerBlock.x),
+                CEIL_DIV(nerr->nrow, threadsPerBlock.y));
+        cudak_(sigmoid_grad)<<<numBlocks, threadsPerBlock>>> \
+            (MATRIX_ELEM_PTR(output), MATRIX_ELEM_PTR(err),
+             MATRIX_ELEM_PTR(nerr),
+             nerr->nrow, nerr->ncol,
+             nerr->stride / sizeof(MATRIX_ELEM));
+    }
+
     void cudak_(cuda_rowsum)(const Matrix *a, Matrix *b) {
         dim3 block(CUDA_THREADS_NN, 1);
         int ncol = a->ncol;
diff --git a/matrix/generic/cumatrix.c b/matrix/generic/cumatrix.c
index 8de6c1b..2b3b9d4 100644
--- a/matrix/generic/cumatrix.c
+++ b/matrix/generic/cumatrix.c
@@ -18,6 +18,12 @@
 #include "driver_types.h"
 #include "cublas_v2.h"
 
+#define CHECK_SAME_DIMENSION(a, b) \
+    do { \
+        if (!(a->nrow == b->nrow && a->ncol == b->ncol)) \
+            nerv_error(L, "Matrices should be of the same dimension"); \
+    } while (0)
+
 static cublasHandle_t cublas_handle;
 
 Matrix *nerv_matrix_(new_)(long nrow, long ncol);
@@ -40,8 +46,7 @@ static int nerv_matrix_(add)(lua_State *L) {
     Matrix *b = luaT_checkudata(L, 3, nerv_matrix_(tname));
     MATRIX_ELEM alpha = luaL_checknumber(L, 4); /* alpha */
     MATRIX_ELEM beta = luaL_checknumber(L, 5); /* alpha */
-    if (!(a->nrow == b->nrow && a->ncol == b->ncol))
-        nerv_error(L, "Matrices should be of the same dimension");
+    CHECK_SAME_DIMENSION(a, b);
     nerv_matrix_(add_)(a, b, c, alpha, beta);
     return 0;
 }
@@ -91,12 +96,23 @@ static int nerv_matrix_(create)(lua_State *L) {
 
 static int nerv_matrix_(sigmoid)(lua_State *L) {
     Matrix *a = luaT_checkudata(L, 1, nerv_matrix_(tname));
-    Matrix *b = nerv_matrix_(new_)(a->nrow, a->ncol);
+    Matrix *b = luaT_checkudata(L, 2, nerv_matrix_(tname));
+    CHECK_SAME_DIMENSION(a, b);
     cudak_(cuda_sigmoid)(a, b);
     luaT_pushudata(L, b, nerv_matrix_(tname));
     return 1;
 }
 
+static int nerv_matrix_(sigmoid_grad)(lua_State *L) {
+    Matrix *nerr = luaT_checkudata(L, 1, nerv_matrix_(tname));
+    Matrix *err = luaT_checkudata(L, 2, nerv_matrix_(tname));
+    Matrix *output = luaT_checkudata(L, 3, nerv_matrix_(tname));
+    CHECK_SAME_DIMENSION(nerr, err);
+    CHECK_SAME_DIMENSION(nerr, output);
+    cudak_(cuda_sigmoid_grad)(output, err, nerr);
+    return 0;
+}
+
 static int nerv_matrix_(softmax)(lua_State *L) {
     Matrix *a = luaT_checkudata(L, 1, nerv_matrix_(tname));
     Matrix *max = nerv_matrix_(new_)(a->nrow, 1);
@@ -158,8 +174,7 @@ extern const char *MATRIX_CUMATRIX_HOST_TNAME;
 static int nerv_matrix_(copy_from)(lua_State *L) {
     Matrix *a = luaT_checkudata(L, 1, nerv_matrix_(tname));
     Matrix *b = luaT_checkudata(L, 2, MATRIX_CUMATRIX_HOST_TNAME);
-    if (!(a->nrow == b->nrow && a->ncol == b->ncol))
-        nerv_error(L, "Matrices should be of the same dimension");
+    CHECK_SAME_DIMENSION(a, b);
     cudaMemcpy2D(MATRIX_ELEM_PTR(a), a->stride,
                 MATRIX_ELEM_PTR(b), b->stride,
                 sizeof(MATRIX_ELEM) * b->ncol, b->nrow,
@@ -170,8 +185,7 @@ static int nerv_matrix_(copy_from)(lua_State *L) {
 static int nerv_matrix_(copy_to)(lua_State *L) {
     Matrix *a = luaT_checkudata(L, 1, nerv_matrix_(tname));
     Matrix *b = luaT_checkudata(L, 2, MATRIX_CUMATRIX_HOST_TNAME);
-    if (!(a->nrow == b->nrow && a->ncol == b->ncol))
-        nerv_error(L, "Matrices should be of the same dimension");
+    CHECK_SAME_DIMENSION(a, b);
     cudaMemcpy2D(MATRIX_ELEM_PTR(b), b->stride,
                 MATRIX_ELEM_PTR(a), a->stride,
                 sizeof(MATRIX_ELEM) * a->ncol, a->nrow,
@@ -197,7 +211,6 @@ static int nerv_matrix_(trans)(lua_State *L) {
 
 static const luaL_Reg nerv_matrix_(extra_methods)[] = {
     {"create", nerv_matrix_(create)},
-    {"sigmoid", nerv_matrix_(sigmoid)},
     {"softmax", nerv_matrix_(softmax)},
     {"colsum", nerv_matrix_(colsum)},
     {"rowsum", nerv_matrix_(rowsum)},
@@ -210,6 +223,8 @@ static const luaL_Reg nerv_matrix_(extra_methods)[] = {
     {"mul", nerv_matrix_(mul)},
     {"add_row", nerv_matrix_(add_row)},
     {"fill", nerv_matrix_(fill)},
+    {"sigmoid", nerv_matrix_(sigmoid)},
+    {"sigmoid_grad", nerv_matrix_(sigmoid_grad)},
     {NULL, NULL}
 };