move dspr to BLAS

Author: hhbyyh

mllib/src/main/scala/org/apache/spark/mllib/linalg/BLAS.scala

@@ -168,6 +168,41 @@ private[spark] object BLAS extends Serializable with Logging {
     sum
   }
 
+  /**
+   * Adds alpha * x * x.t to a matrix in-place. This is the same as BLAS's DSPR.
+   *
+   * @param U the upper triangular part of the matrix packed in an array (column major)
+   */
+  def dspr(alpha: Double, v: Vector, U: Array[Double]): Unit = {
+    val n = v.size
+    v match {
+      case DenseVector(values) =>
+        NativeBLAS.dspr("U", n, alpha, values, 1, U)
+      case SparseVector(size, indices, values) =>
+        val nnz = indices.length
+        var colStartIdx = 0
+        var prevCol = 0
+        var col = 0
+        var j = 0
+        var i = 0
+        var av = 0.0
+        while (j < nnz) {
+          col = indices(j)
+          // Skip empty columns.
+          colStartIdx += (col - prevCol) * (col + prevCol + 1) / 2
+          col = indices(j)
+          av = alpha * values(j)
+          i = 0
+          while (i <= j) {
+            U(colStartIdx + indices(i)) += av * values(i)
+            i += 1
+          }
+          j += 1
+          prevCol = col
+        }
+    }
+  }
+
   /**
    * y = x
    */

mllib/src/main/scala/org/apache/spark/mllib/linalg/distributed/RowMatrix.scala

@@ -24,7 +24,6 @@ import scala.collection.mutable.ListBuffer
 import breeze.linalg.{DenseMatrix => BDM, DenseVector => BDV, SparseVector => BSV, axpy => brzAxpy,
   svd => brzSvd, MatrixSingularException, inv}
 import breeze.numerics.{sqrt => brzSqrt}
-import com.github.fommil.netlib.BLAS.{getInstance => blas}
 
 import org.apache.spark.Logging
 import org.apache.spark.SparkContext._
@@ -123,7 +122,7 @@ class RowMatrix @Since("1.0.0") (
     // Compute the upper triangular part of the gram matrix.
     val GU = rows.treeAggregate(new BDV[Double](new Array[Double](nt)))(
       seqOp = (U, v) => {
-        RowMatrix.dspr(1.0, v, U.data)
+        BLAS.dspr(1.0, v, U.data)
         U
       }, combOp = (U1, U2) => U1 += U2)
 
@@ -673,42 +672,6 @@ class RowMatrix @Since("1.0.0") (
 @Experimental
 object RowMatrix {
 
-  /**
-   * Adds alpha * x * x.t to a matrix in-place. This is the same as BLAS's DSPR.
-   *
-   * @param U the upper triangular part of the matrix packed in an array (column major)
-   */
-  private def dspr(alpha: Double, v: Vector, U: Array[Double]): Unit = {
-    // TODO: Find a better home (breeze?) for this method.
-    val n = v.size
-    v match {
-      case DenseVector(values) =>
-        blas.dspr("U", n, alpha, values, 1, U)
-      case SparseVector(size, indices, values) =>
-        val nnz = indices.length
-        var colStartIdx = 0
-        var prevCol = 0
-        var col = 0
-        var j = 0
-        var i = 0
-        var av = 0.0
-        while (j < nnz) {
-          col = indices(j)
-          // Skip empty columns.
-          colStartIdx += (col - prevCol) * (col + prevCol + 1) / 2
-          col = indices(j)
-          av = alpha * values(j)
-          i = 0
-          while (i <= j) {
-            U(colStartIdx + indices(i)) += av * values(i)
-            i += 1
-          }
-          j += 1
-          prevCol = col
-        }
-    }
-  }
-
   /**
    * Fills a full square matrix from its upper triangular part.
    */