Github user mengxr commented on a diff in the pull request:
https://github.com/apache/spark/pull/2294#discussion_r17704445
--- Diff: mllib/src/main/scala/org/apache/spark/mllib/linalg/BLAS.scala ---
@@ -197,4 +201,368 @@ private[mllib] object BLAS extends Serializable {
throw new IllegalArgumentException(s"scal doesn't support vector
type ${x.getClass}.")
}
}
+
+ // For level-3 routines, we use the native BLAS.
+ private def nativeBLAS: NetlibBLAS = {
+ if (_nativeBLAS == null) {
+ _nativeBLAS = NativeBLAS
+ }
+ _nativeBLAS
+ }
+
+ /**
+ * C := alpha * A * B + beta * C
+ * @param transA specify whether to use matrix A, or the transpose of
matrix A. Should be "N" or
+ * "n" to use A, and "T" or "t" to use the transpose of A.
+ * @param transB specify whether to use matrix B, or the transpose of
matrix B. Should be "N" or
+ * "n" to use B, and "T" or "t" to use the transpose of B.
+ * @param alpha a scalar to scale the multiplication A * B.
+ * @param A the matrix A that will be left multiplied to B. Size of m x
k.
+ * @param B the matrix B that will be left multiplied by A. Size of k x
n.
+ * @param beta a scalar that can be used to scale matrix C.
+ * @param C the resulting matrix C. Size of m x n.
+ */
+ def gemm(
+ transA: Boolean,
+ transB: Boolean,
+ alpha: Double,
+ A: Matrix,
+ B: DenseMatrix,
+ beta: Double,
+ C: DenseMatrix): Unit = {
+ if (alpha == 0.0) {
+ logWarning("gemm: alpha is equal to 0. Returning C.")
--- End diff --
`gemm` maybe called many times and there are cases when `alpha` is indeed
zero. Maybe we can change it to `logDebug` to avoid outputting many log
messages at a normal level.
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