From 39cd2aeb18bdd0a4001a2fc0cb40ff331811f995 Mon Sep 17 00:00:00 2001
From: btracey <tracey.brendan@gmail.com>
Date: Mon, 2 Feb 2015 19:43:47 -0800
Subject: [PATCH] Add symmetric Add function

Remove unnecessary fmt statement
---
 mat64/symmetric.go      | 38 ++++++++++++++++++++++++++++++++++
 mat64/symmetric_test.go | 45 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 83 insertions(+)

diff --git a/mat64/symmetric.go b/mat64/symmetric.go
index 9e73f7d..677eaaa 100644
--- a/mat64/symmetric.go
+++ b/mat64/symmetric.go
@@ -75,6 +75,44 @@ func (s *SymDense) isZero() bool {
 	return s.mat.N == 0
 }
 
+func (s *SymDense) AddSym(a, b Symmetric) {
+	n := a.Symmetric()
+	if n != b.Symmetric() {
+		panic(ErrShape)
+	}
+	if s.isZero() {
+		s.mat = blas64.Symmetric{
+			N:      n,
+			Stride: n,
+			Data:   use(s.mat.Data, n*n),
+			Uplo:   blas.Upper,
+		}
+	} else if s.mat.N != n {
+		panic(ErrShape)
+	}
+
+	if a, ok := a.(RawSymmmetricer); ok {
+		if b, ok := b.(RawSymmmetricer); ok {
+			amat, bmat := a.RawSymmetric(), b.RawSymmetric()
+			for i := 0; i < n; i++ {
+				btmp := bmat.Data[i*bmat.Stride+i : i*bmat.Stride+n]
+				stmp := s.mat.Data[i*s.mat.Stride+i : i*s.mat.Stride+n]
+				for j, v := range amat.Data[i*amat.Stride+i : i*amat.Stride+n] {
+					stmp[j] = v + btmp[j]
+				}
+			}
+			return
+		}
+	}
+
+	for i := 0; i < n; i++ {
+		stmp := s.mat.Data[i*s.mat.Stride : i*s.mat.Stride+n]
+		for j := i; j < n; j++ {
+			stmp[j] = a.At(i, j) + b.At(i, j)
+		}
+	}
+}
+
 func (s *SymDense) CopySym(a Symmetric) int {
 	n := a.Symmetric()
 	n = min(n, s.mat.N)
diff --git a/mat64/symmetric_test.go b/mat64/symmetric_test.go
index a50ed8e..9ca5541 100644
--- a/mat64/symmetric_test.go
+++ b/mat64/symmetric_test.go
@@ -76,6 +76,51 @@ func (s *S) TestSymAtSet(c *check.C) {
 	c.Check(t.At(1, 2), check.Equals, 12.0)
 }
 
+func (s *S) TestSymAdd(c *check.C) {
+	for _, test := range []struct {
+		n int
+	}{
+		{n: 1},
+		{n: 2},
+		{n: 3},
+		{n: 4},
+		{n: 5},
+		{n: 10},
+	} {
+		n := test.n
+		a := NewSymDense(n, nil)
+		for i := range a.mat.Data {
+			a.mat.Data[i] = rand.Float64()
+		}
+		b := NewSymDense(n, nil)
+		for i := range a.mat.Data {
+			b.mat.Data[i] = rand.Float64()
+		}
+		var m Dense
+		m.Add(a, b)
+
+		// Check with new receiver
+		var s SymDense
+		s.AddSym(a, b)
+		for i := 0; i < n; i++ {
+			for j := i; j < n; j++ {
+				v := m.At(i, j)
+				c.Check(s.At(i, j), check.Equals, v)
+			}
+		}
+
+		// Check with equal receiver
+		s.CopySym(a)
+		s.AddSym(&s, b)
+		for i := 0; i < n; i++ {
+			for j := i; j < n; j++ {
+				v := m.At(i, j)
+				c.Check(s.At(i, j), check.Equals, v)
+			}
+		}
+	}
+}
+
 func (s *S) TestCopy(c *check.C) {
 	for _, test := range []struct {
 		n int