Rewrite to match Chromium impl

index.bs

@@ -4326,8 +4326,8 @@ partial interface MLGraphBuilder {
 
 <div>
     **Arguments:**
-        - *a*: an {{MLOperand}}. The first N-dimensional input tensor.
-        - *b*: an {{MLOperand}}. The second N-dimensional input tensor.
+        - *a*: an {{MLOperand}}. The first input tensor which is at least 2-D.
+        - *b*: an {{MLOperand}}. The second input tensor which is at least 2-D.
 
     **Returns:** an {{MLOperand}}. The output tensor that contains the matrix
     product of two input tensors.
@@ -4337,9 +4337,6 @@ partial interface MLGraphBuilder {
         - If both *a* and *b* are 2-dimensional, they are multiplied like conventional
             matrices and produce a 2-dimensional tensor as the output.
         - If either *a* or *b* is `N`-dimensional where `N > 2`, it is treated as a stack of matrices with dimensions corresponding to the last two indices. The matrix multiplication will be broadcasted accordingly by following the [[!numpy-broadcasting-rule]]. The output is a `N`-dimensional tensor whose rank is the maximum [=rank=] of the input tensors. For each dimension, except the last two, of the output tensor, its size is the maximum size along that dimension of the input tensors.
-        - If *a* is 1-dimensional, it is converted to a 2-dimensional tensor by prepending a 1 to its dimensions.
-        - If *b* is 1-dimensional, it is converted to a 2-dimensional tensor by by appending a 1 to its dimensions.
-        - If both *a* and *b* are 1-dimensional, the operation is a vector dot-product, which produces a scalar output.
 </div>
 
 <details open algorithm>
@@ -4351,16 +4348,19 @@ partial interface MLGraphBuilder {
     1. Let |sizeA| be the [=list/size=] of |shapeA|.
     1. Let |shapeB| be a [=list/clone=] of |b|.{{MLOperand/[[descriptor]]}}.{{MLOperandDescriptor/dimensions}}.
     1. Let |sizeB| be the [=list/size=] of |shapeB|.
-    1. If |sizeA| and |sizeB| is 1, return «  1  ».
-    1. If |sizeA| is 1, then [=list/prepend=] 1 to |shapeA| and set |sizeA| to 2.
-    1. If |shapeA|[0] is not equal to |shapeB|[|sizeB| - 2], then [=exception/throw=] an "{{OperationError}}" {{DOMException}}.
-    1. If |sizeB| is 1, then [=list/append=] 1 to |shapeB| and set |sizeB| to 2.
-    1. If |shapeA|[|sizeA| - 1] is not equal to |shapeB|[0], then [=exception/throw=] an "{{OperationError}}" {{DOMException}}.
-    1. Let |size| be the maximum of |sizeA| and |sizeB|.
-    1. Let |shape| be a new [=/list=].
-    1. [=list/For each=] |index| in [=the range=] 0 to |size|, exclusive:
-        1. [=list/Append=] the maximum of |shapeA|[|index|] and |shapeB|[|index|] to |shape|.
-    1. Return |shape|.
+    1. If either |sizeA| or |sizeB| is less than 2, then [=exception/throw=] a "{{DataError}}" {{DOMException}}.
+    1. Let |colsA| be |shapeA|[|sizeA| - 1].
+    1. Let |rowsA| be |shapeA|[|sizeA| - 2].
+    1. Let |colsB| be |shapeB|[|sizeB| - 1].
+    1. Let |rowsB| be |shapeB|[|sizeB| - 2].
+    1. If |colsA| is not equal to |rowsB|, then [=exception/throw=] a "{{DataError}}" {{DOMException}}.
+    1. Let |slicedA| be a [=list/clone=] of |shapeA| with the last 2 items [=list/removed=].
+    1. Let |slicedB| be a [=list/clone=] of |shapeB| with the last 2 items [=list/removed=].
+    1. If both |sizeA| and |sizeB| are greater than 2, then let |outputShape| be the result of [=bidirectionally broadcasting the shapes=] |slicedA| and |slicedB|. If that returns failure, then [=exception/throw=] a "{{DataError}}" {{DOMException}}.
+    1. Otherwise, if both |sizeA| and |sizeB| are equal to 2, then let |outputShape| be an empty [=/list=].
+    1. Otherwise, let |outputShape| be the [=list/size|longer=] of |slicedA| or |slicedB|.
+    1. [=list/Append=] « |rowsA|, |colsB| » to |outputShape|.
+    1. Return |outputShape|.
   </div>
 </details>