From 32e5174ac5a57307d9e46bb1e02d3031a5afea4e Mon Sep 17 00:00:00 2001
From: Determinant <ted.sybil@gmail.com>
Date: Tue, 19 May 2015 15:21:52 +0800
Subject: add subtraction for cumatrix

---
 cumatrix_example.lua      |  8 ++++++--
 matrix/generic/cumatrix.c | 41 +++++++++++++++++++++++++++++------------
 2 files changed, 35 insertions(+), 14 deletions(-)

diff --git a/cumatrix_example.lua b/cumatrix_example.lua
index f26d7f4..aeb5828 100644
--- a/cumatrix_example.lua
+++ b/cumatrix_example.lua
@@ -11,6 +11,10 @@ for i = 0, m - 1 do
     end
 end
 print(fm)
-print(fm:softmax())
+fs = fm:softmax()
+print(fs)
 print(dm)
-print(dm:softmax())
+ds = dm:softmax()
+print(ds)
+print(fs + fs)
+print(fs - fs)
diff --git a/matrix/generic/cumatrix.c b/matrix/generic/cumatrix.c
index f0ef99d..7afa51a 100644
--- a/matrix/generic/cumatrix.c
+++ b/matrix/generic/cumatrix.c
@@ -20,28 +20,44 @@
 static cublasHandle_t cublas_handle;
 
 Matrix *nerv_matrix_(new_)(long nrow, long ncol);
-static int nerv_matrix_(add)(lua_State *L) {
-    Matrix *a = luaT_checkudata(L, 1, nerv_matrix_(tname));
-    Matrix *b = luaT_checkudata(L, 2, nerv_matrix_(tname));
-    Matrix *c;
-    long nrow, ncol;
-    if (!(a->nrow == b->nrow && a->ncol == b->ncol))
-        nerv_error(L, "Matrices should be of the same dimension");
-    nrow = a->nrow;
-    ncol = a->ncol;
-    c = nerv_matrix_(new_)(nrow, ncol);
-    MATRIX_ELEM alpha = 1.0f, beta = 1.0f;
+
+static void nerv_matrix_(add_)(const Matrix *a, const Matrix *b,
+                                const Matrix *c,
+                                MATRIX_ELEM alpha, MATRIX_ELEM beta) {
     NERV_CUBLAS_(geam)(cublas_handle, CUBLAS_OP_N, CUBLAS_OP_N,
-                ncol, nrow,
+                a->ncol, a->nrow,
                 &alpha,
                 MATRIX_ELEM_PTR(a), a->stride / sizeof(MATRIX_ELEM),
                 &beta,
                 MATRIX_ELEM_PTR(b), b->stride / sizeof(MATRIX_ELEM),
                 MATRIX_ELEM_PTR(c), c->stride / sizeof(MATRIX_ELEM));
+}
+
+static int nerv_matrix_(add)(lua_State *L) {
+    Matrix *a = luaT_checkudata(L, 1, nerv_matrix_(tname));
+    Matrix *b = luaT_checkudata(L, 2, nerv_matrix_(tname));
+    Matrix *c;
+    if (!(a->nrow == b->nrow && a->ncol == b->ncol))
+        nerv_error(L, "Matrices should be of the same dimension");
+    c = nerv_matrix_(new_)(a->nrow, a->ncol);
+    nerv_matrix_(add_)(a, b, c, 1.0f, 1.0f);
+    luaT_pushudata(L, c, nerv_matrix_(tname));
+    return 1;
+}
+
+static int nerv_matrix_(sub)(lua_State *L) {
+    Matrix *a = luaT_checkudata(L, 1, nerv_matrix_(tname));
+    Matrix *b = luaT_checkudata(L, 2, nerv_matrix_(tname));
+    Matrix *c;
+    if (!(a->nrow == b->nrow && a->ncol == b->ncol))
+        nerv_error(L, "Matrices should be of the same dimension");
+    c = nerv_matrix_(new_)(a->nrow, a->ncol);
+    nerv_matrix_(add_)(a, b, c, 1.0f, -1.0f);
     luaT_pushudata(L, c, nerv_matrix_(tname));
     return 1;
 }
 
+
 static int nerv_matrix_(mul)(lua_State *L) {
     Matrix *a = luaT_checkudata(L, 1, nerv_matrix_(tname));
     Matrix *b = luaT_checkudata(L, 2, nerv_matrix_(tname));
@@ -99,6 +115,7 @@ static int nerv_matrix_(colmax)(lua_State *L) {
 
 static const luaL_Reg nerv_matrix_(extra_methods)[] = {
     {"__add__", nerv_matrix_(add)},
+    {"__sub__", nerv_matrix_(sub)},
     {"__mul__", nerv_matrix_(mul)},
     {"sigmoid", nerv_matrix_(sigmoid)},
     {"softmax", nerv_matrix_(softmax)},
-- 
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