From 848874e1b793284e6e95c55ef99c9839a60e849f Mon Sep 17 00:00:00 2001
From: Christoph Ruegg <git@cdrnet.ch>
Date: Fri, 20 Jun 2014 00:37:31 +0200
Subject: [PATCH] LA: CoerceZero for matrices and vectors (via MapInplace)

---
 src/Numerics/LinearAlgebra/Complex/Matrix.cs   |  9 ++++++++-
 src/Numerics/LinearAlgebra/Complex/Vector.cs   |  8 ++++++++
 src/Numerics/LinearAlgebra/Complex32/Matrix.cs |  8 ++++++++
 src/Numerics/LinearAlgebra/Complex32/Vector.cs |  8 ++++++++
 src/Numerics/LinearAlgebra/Double/Matrix.cs    |  8 ++++++++
 src/Numerics/LinearAlgebra/Double/Vector.cs    |  8 ++++++++
 src/Numerics/LinearAlgebra/Matrix.cs           | 13 +++++++++++++
 src/Numerics/LinearAlgebra/Single/Matrix.cs    |  8 ++++++++
 src/Numerics/LinearAlgebra/Single/Vector.cs    |  8 ++++++++
 src/Numerics/LinearAlgebra/Vector.cs           | 13 +++++++++++++
 10 files changed, 90 insertions(+), 1 deletion(-)

diff --git a/src/Numerics/LinearAlgebra/Complex/Matrix.cs b/src/Numerics/LinearAlgebra/Complex/Matrix.cs
index fe7de0c2..4c28604e 100644
--- a/src/Numerics/LinearAlgebra/Complex/Matrix.cs
+++ b/src/Numerics/LinearAlgebra/Complex/Matrix.cs
@@ -41,7 +41,6 @@ namespace MathNet.Numerics.LinearAlgebra.Complex
     using Complex = Numerics.Complex;
 #else
     using Complex = System.Numerics.Complex;
-
 #endif
 
     /// <summary>
@@ -58,6 +57,14 @@ namespace MathNet.Numerics.LinearAlgebra.Complex
         {
         }
 
+        /// <summary>
+        /// Set all values whose absolute value is smaller than the threshold to zero.
+        /// </summary>
+        public override void CoerceZero(double threshold)
+        {
+            MapInplace(x => x.Magnitude < threshold ? Complex.Zero : x, Zeros.AllowSkip);
+        }
+
         /// <summary>Calculates the induced L1 norm of this matrix.</summary>
         /// <returns>The maximum absolute column sum of the matrix.</returns>
         public override double L1Norm()
diff --git a/src/Numerics/LinearAlgebra/Complex/Vector.cs b/src/Numerics/LinearAlgebra/Complex/Vector.cs
index 22f82db2..6cda7da6 100644
--- a/src/Numerics/LinearAlgebra/Complex/Vector.cs
+++ b/src/Numerics/LinearAlgebra/Complex/Vector.cs
@@ -55,6 +55,14 @@ namespace MathNet.Numerics.LinearAlgebra.Complex
         {
         }
 
+        /// <summary>
+        /// Set all values whose absolute value is smaller than the threshold to zero.
+        /// </summary>
+        public override void CoerceZero(double threshold)
+        {
+            MapInplace(x => x.Magnitude < threshold ? Complex.Zero : x, Zeros.AllowSkip);
+        }
+
         /// <summary>
         /// Adds a scalar to each element of the vector and stores the result in the result vector.
         /// </summary>
diff --git a/src/Numerics/LinearAlgebra/Complex32/Matrix.cs b/src/Numerics/LinearAlgebra/Complex32/Matrix.cs
index cf988d1b..19d418ed 100644
--- a/src/Numerics/LinearAlgebra/Complex32/Matrix.cs
+++ b/src/Numerics/LinearAlgebra/Complex32/Matrix.cs
@@ -52,6 +52,14 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32
         {
         }
 
+        /// <summary>
+        /// Set all values whose absolute value is smaller than the threshold to zero.
+        /// </summary>
+        public override void CoerceZero(double threshold)
+        {
+            MapInplace(x => x.Magnitude < threshold ? Complex32.Zero : x, Zeros.AllowSkip);
+        }
+
         /// <summary>Calculates the induced L1 norm of this matrix.</summary>
         /// <returns>The maximum absolute column sum of the matrix.</returns>
         public override double L1Norm()
diff --git a/src/Numerics/LinearAlgebra/Complex32/Vector.cs b/src/Numerics/LinearAlgebra/Complex32/Vector.cs
index a2fa809e..865296d5 100644
--- a/src/Numerics/LinearAlgebra/Complex32/Vector.cs
+++ b/src/Numerics/LinearAlgebra/Complex32/Vector.cs
@@ -50,6 +50,14 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32
         {
         }
 
+        /// <summary>
+        /// Set all values whose absolute value is smaller than the threshold to zero.
+        /// </summary>
+        public override void CoerceZero(double threshold)
+        {
+            MapInplace(x => x.Magnitude < threshold ? Complex32.Zero : x, Zeros.AllowSkip);
+        }
+
         /// <summary>
         /// Adds a scalar to each element of the vector and stores the result in the result vector.
         /// </summary>
diff --git a/src/Numerics/LinearAlgebra/Double/Matrix.cs b/src/Numerics/LinearAlgebra/Double/Matrix.cs
index 32766df8..57224988 100644
--- a/src/Numerics/LinearAlgebra/Double/Matrix.cs
+++ b/src/Numerics/LinearAlgebra/Double/Matrix.cs
@@ -50,6 +50,14 @@ namespace MathNet.Numerics.LinearAlgebra.Double
         {
         }
 
+        /// <summary>
+        /// Set all values whose absolute value is smaller than the threshold to zero.
+        /// </summary>
+        public override void CoerceZero(double threshold)
+        {
+            MapInplace(x => Math.Abs(x) < threshold ? 0d : x, Zeros.AllowSkip);
+        }
+
         /// <summary>Calculates the induced L1 norm of this matrix.</summary>
         /// <returns>The maximum absolute column sum of the matrix.</returns>
         public override double L1Norm()
diff --git a/src/Numerics/LinearAlgebra/Double/Vector.cs b/src/Numerics/LinearAlgebra/Double/Vector.cs
index 9f4599d4..01e80270 100644
--- a/src/Numerics/LinearAlgebra/Double/Vector.cs
+++ b/src/Numerics/LinearAlgebra/Double/Vector.cs
@@ -48,6 +48,14 @@ namespace MathNet.Numerics.LinearAlgebra.Double
         {
         }
 
+        /// <summary>
+        /// Set all values whose absolute value is smaller than the threshold to zero.
+        /// </summary>
+        public override void CoerceZero(double threshold)
+        {
+            MapInplace(x => Math.Abs(x) < threshold ? 0d : x, Zeros.AllowSkip);
+        }
+
         /// <summary>
         /// Adds a scalar to each element of the vector and stores the result in the result vector.
         /// </summary>
diff --git a/src/Numerics/LinearAlgebra/Matrix.cs b/src/Numerics/LinearAlgebra/Matrix.cs
index ba11a741..13d2add5 100644
--- a/src/Numerics/LinearAlgebra/Matrix.cs
+++ b/src/Numerics/LinearAlgebra/Matrix.cs
@@ -240,6 +240,19 @@ namespace MathNet.Numerics.LinearAlgebra
             Storage.Clear(rowIndex, rowCount, columnIndex, columnCount);
         }
 
+        /// <summary>
+        /// Set all values whose absolute value is smaller than the threshold to zero, in-place.
+        /// </summary>
+        public abstract void CoerceZero(double threshold);
+
+        /// <summary>
+        /// Set all values that meet the predicate to zero, in-place.
+        /// </summary>
+        public void CoerceZero(Func<T, bool> zeroPredicate)
+        {
+            MapInplace(x => zeroPredicate(x) ? Zero : x, Zeros.AllowSkip);
+        }
+
         /// <summary>
         /// Creates a clone of this instance.
         /// </summary>
diff --git a/src/Numerics/LinearAlgebra/Single/Matrix.cs b/src/Numerics/LinearAlgebra/Single/Matrix.cs
index c5898764..f941a595 100644
--- a/src/Numerics/LinearAlgebra/Single/Matrix.cs
+++ b/src/Numerics/LinearAlgebra/Single/Matrix.cs
@@ -50,6 +50,14 @@ namespace MathNet.Numerics.LinearAlgebra.Single
         {
         }
 
+        /// <summary>
+        /// Set all values whose absolute value is smaller than the threshold to zero.
+        /// </summary>
+        public override void CoerceZero(double threshold)
+        {
+            MapInplace(x => Math.Abs(x) < threshold ? 0f : x, Zeros.AllowSkip);
+        }
+
         /// <summary>Calculates the induced L1 norm of this matrix.</summary>
         /// <returns>The maximum absolute column sum of the matrix.</returns>
         public override double L1Norm()
diff --git a/src/Numerics/LinearAlgebra/Single/Vector.cs b/src/Numerics/LinearAlgebra/Single/Vector.cs
index bea3e5a1..0ff911fa 100644
--- a/src/Numerics/LinearAlgebra/Single/Vector.cs
+++ b/src/Numerics/LinearAlgebra/Single/Vector.cs
@@ -48,6 +48,14 @@ namespace MathNet.Numerics.LinearAlgebra.Single
         {
         }
 
+        /// <summary>
+        /// Set all values whose absolute value is smaller than the threshold to zero.
+        /// </summary>
+        public override void CoerceZero(double threshold)
+        {
+            MapInplace(x => Math.Abs(x) < threshold ? 0f : x, Zeros.AllowSkip);
+        }
+
         /// <summary>
         /// Adds a scalar to each element of the vector and stores the result in the result vector.
         /// </summary>
diff --git a/src/Numerics/LinearAlgebra/Vector.cs b/src/Numerics/LinearAlgebra/Vector.cs
index a32839d5..074335d7 100644
--- a/src/Numerics/LinearAlgebra/Vector.cs
+++ b/src/Numerics/LinearAlgebra/Vector.cs
@@ -132,6 +132,19 @@ namespace MathNet.Numerics.LinearAlgebra
             Storage.Clear(index, count);
         }
 
+        /// <summary>
+        /// Set all values whose absolute value is smaller than the threshold to zero, in-place.
+        /// </summary>
+        public abstract void CoerceZero(double threshold);
+
+        /// <summary>
+        /// Set all values that meet the predicate to zero, in-place.
+        /// </summary>
+        public void CoerceZero(Func<T, bool> zeroPredicate)
+        {
+            MapInplace(x => zeroPredicate(x) ? Zero : x, Zeros.AllowSkip);
+        }
+
         /// <summary>
         /// Returns a deep-copy clone of the vector.
         /// </summary>