From: Francois Fleuret <francois@fleuret.org>
Date: Mon, 25 Jul 2022 13:31:18 +0000 (+0200)
Subject: Added the (missing) W_o
X-Git-Url: https://fleuret.org/cgi-bin/gitweb/gitweb.cgi?a=commitdiff_plain;h=9c62741f73c7bbcd00bafad84cd31325b358ef1d;p=mygpt.git

Added the (missing) W_o
---

diff --git a/mygpt.py b/mygpt.py
index 4951460..42960b1 100755
--- a/mygpt.py
+++ b/mygpt.py
@@ -51,6 +51,7 @@ class QKVAttention(nn.Module):
         self.w_q = randw(nb_heads, dim_qk, dim_in)
         self.w_k = randw(nb_heads, dim_qk, dim_in)
         self.w_v = randw(nb_heads, dim_v, dim_in)
+        self.w_o = randw(nb_heads, dim_in, dim_v)
         self.causal = causal
         self.attention_dropout = attention_dropout
 
@@ -61,12 +62,15 @@ class QKVAttention(nn.Module):
         v = torch.einsum('ntc,hdc->nhtd', x_kv, self.w_v)
         a = torch.einsum('nhtd,nhsd->nhts', q, k) / math.sqrt(q.size(3))
         if self.causal:
-            mask = torch.tril(q.new_ones(a.size(2), a.size(3)))[None, None, :, :] == 0
+            mask = torch.arange(a.size(2), device = q.device)[None, None, :, None] \
+                   < torch.arange(a.size(3), device = q.device)[None, None, None, :]
             a = a.masked_fill(mask, float('-inf'))
         a = a.softmax(dim = 3)
         a = F.dropout(a, self.attention_dropout, self.training)
         y = torch.einsum('nhts,nhsd->nhtd', a, v)
-        return y.permute(0, 2, 1, 3).flatten(2) # nhtd -> nt(hd)
+        y = torch.einsum('nhtd,hcd->ntc', y, self.w_o)
+
+        return y
 
 ##############################
 
@@ -122,6 +126,8 @@ class MyGPT(nn.Module):
 ######################################################################
 
 if __name__ == '__main__':
+    print('Basic check.')
+
     vocabulary_size = 10
     x = torch.randint(vocabulary_size, (25, 100))