LA: avoid some redundant range checks (perf)

src/Numerics/Distributions/Multivariate/InverseWishart.cs

@@ -121,7 +121,7 @@ namespace MathNet.Numerics.Distributions
 
             for (var i = 0; i < s.RowCount; i++)
             {
-                if (s[i, i] <= 0.0)
+                if (s.At(i, i) <= 0.0)
                 {
                     return false;
                 }

src/Numerics/Distributions/Multivariate/MatrixNormal.cs

@@ -190,7 +190,7 @@ namespace MathNet.Numerics.Distributions
 
             for (var i = 0; i < v.RowCount; i++)
             {
-                if (v[i, i] <= 0)
+                if (v.At(i, i) <= 0)
                 {
                     return false;
                 }
@@ -198,7 +198,7 @@ namespace MathNet.Numerics.Distributions
 
             for (var i = 0; i < k.RowCount; i++)
             {
-                if (k[i, i] <= 0)
+                if (k.At(i, i) <= 0)
                 {
                     return false;
                 }
@@ -291,7 +291,7 @@ namespace MathNet.Numerics.Distributions
             {
                 for (var j = 0; j < p; j++)
                 {
-                    r[i, j] += vector[(j * n) + i];
+                    r.At(i, j, r.At(i, j) + vector[(j * n) + i]);
                 }
             }
 

src/Numerics/Distributions/Multivariate/Wishart.cs

@@ -114,7 +114,7 @@ namespace MathNet.Numerics.Distributions
 
             for (var i = 0; i < s.RowCount; i++)
             {
-                if (s[i, i] <= 0.0)
+                if (s.At(i, i) <= 0.0)
                 {
                     return false;
                 }
@@ -316,14 +316,14 @@ namespace MathNet.Numerics.Distributions
             var a = new DenseMatrix(count, count, 0.0);
             for (var d = 0; d < count; d++)
             {
-                a[d, d] = Math.Sqrt(Gamma.Sample(rnd, (nu - d) / 2.0, 0.5));
+                a.At(d, d, Math.Sqrt(Gamma.Sample(rnd, (nu - d)/2.0, 0.5)));
             }
 
             for (var i = 1; i < count; i++)
             {
                 for (var j = 0; j < i; j++)
                 {
-                    a[i, j] = Normal.Sample(rnd, 0.0, 1.0);
+                    a.At(i, j, Normal.Sample(rnd, 0.0, 1.0));
                 }
             }
 

src/Numerics/LinearAlgebra/Complex/DenseVector.cs

@@ -172,7 +172,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex
             var matrix = new DenseMatrix(Count, 1);
             for (var i = 0; i < Data.Length; i++)
             {
-                matrix[i, 0] = Data[i];
+                matrix.At(i, 0, Data[i]);
             }
 
             return matrix;
@@ -187,7 +187,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex
             var matrix = new DenseMatrix(1, Count);
             for (var i = 0; i < Data.Length; i++)
             {
-                matrix[0, i] = Data[i];
+                matrix.At(0, i, Data[i]);
             }
 
             return matrix;

src/Numerics/LinearAlgebra/Complex/DiagonalMatrix.cs

@@ -951,7 +951,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex
             result.Clear();
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
         }
 
@@ -1016,7 +1016,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex
             result.Clear();
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
         }
 
@@ -1236,7 +1236,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex
             // Copy the diagonal part into the result matrix.
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
 
             // Copy the lower matrix into the result matrix.
@@ -1244,7 +1244,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex
             {
                 for (var j = 0; j < lower.ColumnCount; j++)
                 {
-                    result[i + RowCount, j] = lower[i, j];
+                    result.At(i + RowCount, j, lower.At(i, j));
                 }
             }
         }
@@ -1304,7 +1304,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex
             // Copy the diagonal part into the result matrix.
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
 
             // Copy the lower matrix into the result matrix.
@@ -1312,7 +1312,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex
             {
                 for (var j = 0; j < right.ColumnCount; j++)
                 {
-                    result[i, j + RowCount] = right[i, j];
+                    result.At(i, j + RowCount, right.At(i, j));
                 }
             }
         }
@@ -1368,7 +1368,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex
             // Copy the diagonal part into the result matrix.
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
 
             // Copy the lower matrix into the result matrix.

src/Numerics/LinearAlgebra/Complex/Factorization/DenseEvd.cs

@@ -83,7 +83,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex.Factorization
             {
                 for (var j = 0; j < order & IsSymmetric; j++)
                 {
-                    IsSymmetric &= matrix[i, j] == matrix[j, i].Conjugate();
+                    IsSymmetric &= matrix.At(i, j) == matrix.At(j, i).Conjugate();
                 }
             }
 
@@ -870,7 +870,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex.Factorization
                             value += ((DenseMatrix)MatrixEv).Data[(i * order) + j] * tmp[i];
                         }
 
-                        result[j, k] = value;
+                        result.At(j, k, value);
                     }
                 }
             }

src/Numerics/LinearAlgebra/Complex/Factorization/UserEvd.cs

@@ -83,7 +83,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex.Factorization
             {
                 for (var j = 0; j < order & IsSymmetric; j++)
                 {
-                    IsSymmetric &= matrix[i, j] == matrix[j, i].Conjugate();
+                    IsSymmetric &= matrix.At(i, j) == matrix.At(j, i).Conjugate();
                 }
             }
 
@@ -865,7 +865,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex.Factorization
                             value += MatrixEv.At(j, i) * tmp[i];
                         }
 
-                        result[j, k] = value;
+                        result.At(j, k, value);
                     }
                 }
             }

src/Numerics/LinearAlgebra/Complex/Factorization/UserSvd.cs

@@ -866,7 +866,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex.Factorization
                         value += MatrixVT.At(i, j).Conjugate() * tmp[i];
                     }
 
-                    result[j, k] = value;
+                    result.At(j, k, value);
                 }
             }
         }

src/Numerics/LinearAlgebra/Complex/Solvers/Preconditioners/Diagonal.cs

@@ -54,7 +54,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex.Solvers.Preconditioners
             var result = new DiagonalMatrix(_inverseDiagonals.Length);
             for (var i = 0; i < _inverseDiagonals.Length; i++)
             {
-                result[i, i] = 1 / _inverseDiagonals[i];
+                result.At(i, i, 1 / _inverseDiagonals[i]);
             }
 
             return result;
@@ -82,7 +82,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex.Solvers.Preconditioners
             _inverseDiagonals = new Complex[matrix.RowCount];
             for (var i = 0; i < matrix.RowCount; i++)
             {
-                _inverseDiagonals[i] = 1 / matrix[i, i];
+                _inverseDiagonals[i] = 1 / matrix.At(i, i);
             }
         }
 

src/Numerics/LinearAlgebra/Complex32/DenseVector.cs

@@ -173,7 +173,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32
             var matrix = new DenseMatrix(Count, 1);
             for (var i = 0; i < Data.Length; i++)
             {
-                matrix[i, 0] = Data[i];
+                matrix.At(i, 0, Data[i]);
             }
 
             return matrix;
@@ -188,7 +188,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32
             var matrix = new DenseMatrix(1, Count);
             for (var i = 0; i < Data.Length; i++)
             {
-                matrix[0, i] = Data[i];
+                matrix.At(0, i, Data[i]);
             }
 
             return matrix;

src/Numerics/LinearAlgebra/Complex32/DiagonalMatrix.cs

@@ -951,7 +951,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32
             result.Clear();
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
         }
 
@@ -1016,7 +1016,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32
             result.Clear();
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
         }
 
@@ -1236,7 +1236,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32
             // Copy the diagonal part into the result matrix.
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
 
             // Copy the lower matrix into the result matrix.
@@ -1244,7 +1244,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32
             {
                 for (var j = 0; j < lower.ColumnCount; j++)
                 {
-                    result[i + RowCount, j] = lower[i, j];
+                    result.At(i + RowCount, j, lower.At(i, j));
                 }
             }
         }
@@ -1304,7 +1304,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32
             // Copy the diagonal part into the result matrix.
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
 
             // Copy the lower matrix into the result matrix.
@@ -1312,7 +1312,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32
             {
                 for (var j = 0; j < right.ColumnCount; j++)
                 {
-                    result[i, j + RowCount] = right[i, j];
+                    result.At(i, j + RowCount, right.At(i, j));
                 }
             }
         }
@@ -1368,7 +1368,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32
             // Copy the diagonal part into the result matrix.
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
 
             // Copy the lower matrix into the result matrix.

src/Numerics/LinearAlgebra/Complex32/Factorization/DenseEvd.cs

@@ -84,7 +84,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32.Factorization
             {
                 for (var j = 0; j < order & IsSymmetric; j++)
                 {
-                    IsSymmetric &= matrix[i, j] == matrix[j, i].Conjugate();
+                    IsSymmetric &= matrix.At(i, j) == matrix.At(j, i).Conjugate();
                 }
             }
 
@@ -874,7 +874,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32.Factorization
                             value += ((DenseMatrix)MatrixEv).Data[(i * order) + j] * tmp[i];
                         }
 
-                        result[j, k] = value;
+                        result.At(j, k, value);
                     }
                 }
             }

src/Numerics/LinearAlgebra/Complex32/Factorization/UserEvd.cs

@@ -84,7 +84,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32.Factorization
             {
                 for (var j = 0; j < order & IsSymmetric; j++)
                 {
-                    IsSymmetric &= matrix[i, j] == matrix[j, i].Conjugate();
+                    IsSymmetric &= matrix.At(i, j) == matrix.At(j, i).Conjugate();
                 }
             }
 
@@ -869,7 +869,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32.Factorization
                             value += MatrixEv.At(j, i) * tmp[i];
                         }
 
-                        result[j, k] = value;
+                        result.At(j, k, value);
                     }
                 }
             }

src/Numerics/LinearAlgebra/Complex32/Factorization/UserSvd.cs

@@ -866,7 +866,7 @@ namespace MathNet.Numerics.LinearAlgebra.Complex32.Factorization
                         value += MatrixVT.At(i, j).Conjugate() * tmp[i];
                     }
 
-                    result[j, k] = value;
+                    result.At(j, k, value);
                 }
             }
         }

src/Numerics/LinearAlgebra/Double/DenseVector.cs

@@ -181,7 +181,7 @@ namespace MathNet.Numerics.LinearAlgebra.Double
             var matrix = new DenseMatrix(Count, 1);
             for (var i = 0; i < Data.Length; i++)
             {
-                matrix[i, 0] = Data[i];
+                matrix.At(i, 0, Data[i]);
             }
 
             return matrix;
@@ -196,7 +196,7 @@ namespace MathNet.Numerics.LinearAlgebra.Double
             var matrix = new DenseMatrix(1, Count);
             for (var i = 0; i < Data.Length; i++)
             {
-                matrix[0, i] = Data[i];
+                matrix.At(0, i, Data[i]);
             }
 
             return matrix;

src/Numerics/LinearAlgebra/Double/DiagonalMatrix.cs

@@ -945,7 +945,7 @@ namespace MathNet.Numerics.LinearAlgebra.Double
             result.Clear();
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
         }
 
@@ -1010,7 +1010,7 @@ namespace MathNet.Numerics.LinearAlgebra.Double
             result.Clear();
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
         }
 
@@ -1230,7 +1230,7 @@ namespace MathNet.Numerics.LinearAlgebra.Double
             // Copy the diagonal part into the result matrix.
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
 
             // Copy the lower matrix into the result matrix.
@@ -1238,7 +1238,7 @@ namespace MathNet.Numerics.LinearAlgebra.Double
             {
                 for (var j = 0; j < lower.ColumnCount; j++)
                 {
-                    result[i + RowCount, j] = lower[i, j];
+                    result.At(i + RowCount, j, lower.At(i, j));
                 }
             }
         }
@@ -1298,7 +1298,7 @@ namespace MathNet.Numerics.LinearAlgebra.Double
             // Copy the diagonal part into the result matrix.
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
 
             // Copy the lower matrix into the result matrix.
@@ -1306,7 +1306,7 @@ namespace MathNet.Numerics.LinearAlgebra.Double
             {
                 for (var j = 0; j < right.ColumnCount; j++)
                 {
-                    result[i, j + RowCount] = right[i, j];
+                    result.At(i, j + RowCount, right.At(i, j));
                 }
             }
         }
@@ -1362,7 +1362,7 @@ namespace MathNet.Numerics.LinearAlgebra.Double
             // Copy the diagonal part into the result matrix.
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
 
             // Copy the lower matrix into the result matrix.

src/Numerics/LinearAlgebra/Double/Factorization/DenseEvd.cs

@@ -83,7 +83,7 @@ namespace MathNet.Numerics.LinearAlgebra.Double.Factorization
             {
                 for (var j = 0; j < order & IsSymmetric; j++)
                 {
-                    IsSymmetric &= matrix[i, j] == matrix[j, i];
+                    IsSymmetric &= matrix.At(i, j) == matrix.At(j, i);
                 }
             }
 
@@ -108,7 +108,7 @@ namespace MathNet.Numerics.LinearAlgebra.Double.Factorization
 
             for (var i = 0; i < order; i++)
             {
-                MatrixD[i, i] = d[i];
+                MatrixD.At(i, i, d[i]);
 
                 if (e[i] > 0)
                 {
@@ -1142,7 +1142,7 @@ namespace MathNet.Numerics.LinearAlgebra.Double.Factorization
                             value += ((DenseMatrix)MatrixEv).Data[(i * order) + j] * tmp[i];
                         }
 
-                        result[j, k] = value;
+                        result.At(j, k, value);
                     }
                 }
             }

src/Numerics/LinearAlgebra/Double/Factorization/UserEvd.cs

@@ -83,7 +83,7 @@ namespace MathNet.Numerics.LinearAlgebra.Double.Factorization
             {
                 for (var j = 0; j < order & IsSymmetric; j++)
                 {
-                    IsSymmetric &= matrix[i, j] == matrix[j, i];
+                    IsSymmetric &= matrix.At(i, j) == matrix.At(j, i);
                 }
             }
 
@@ -108,7 +108,7 @@ namespace MathNet.Numerics.LinearAlgebra.Double.Factorization
 
             for (var i = 0; i < order; i++)
             {
-                MatrixD[i, i] = d[i];
+                MatrixD.At(i, i, d[i]);
 
                 if (e[i] > 0)
                 {
@@ -1138,7 +1138,7 @@ namespace MathNet.Numerics.LinearAlgebra.Double.Factorization
                             value += MatrixEv.At(j, i) * tmp[i];
                         }
 
-                        result[j, k] = value;
+                        result.At(j, k, value);
                     }
                 }
             }

src/Numerics/LinearAlgebra/Double/Factorization/UserSvd.cs

@@ -850,7 +850,7 @@ namespace MathNet.Numerics.LinearAlgebra.Double.Factorization
                         value += MatrixVT.At(i, j) * tmp[i];
                     }
 
-                    result[j, k] = value;
+                    result.At(j, k, value);
                 }
             }
         }

src/Numerics/LinearAlgebra/Generic/Matrix.cs

@@ -1165,7 +1165,7 @@ namespace MathNet.Numerics.LinearAlgebra.Generic
             {
                 for (int i = rowIndex, ii = 0; i < rowMax; i++, ii++)
                 {
-                    At(i, j, subMatrix[ii, j - columnIndex]);
+                    At(i, j, subMatrix.At(ii, j - columnIndex));
                 }
             }
         }
@@ -1438,7 +1438,7 @@ namespace MathNet.Numerics.LinearAlgebra.Generic
                 {
                     var col = i%ColumnCount;
                     var row = (i - col)/RowCount;
-                    hash = hash*31 + this[row, col].GetHashCode();
+                    hash = hash*31 + At(row, col).GetHashCode();
                 }
             }
             return hash;

src/Numerics/LinearAlgebra/Generic/Vector.cs

@@ -1303,7 +1303,7 @@ namespace MathNet.Numerics.LinearAlgebra.Generic
             var matrix = CreateMatrix(Count, 1);
             for (var i = 0; i < Count; i++)
             {
-                matrix[i, 0] = this[i];
+                matrix.At(i, 0, this[i]);
             }
 
             return matrix;
@@ -1320,7 +1320,7 @@ namespace MathNet.Numerics.LinearAlgebra.Generic
             var matrix = CreateMatrix(1, Count);
             for (var i = 0; i < Count; i++)
             {
-                matrix[0, i] = this[i];
+                matrix.At(0, i, this[i]);
             }
 
             return matrix;

src/Numerics/LinearAlgebra/Single/DenseVector.cs

@@ -181,7 +181,7 @@ namespace MathNet.Numerics.LinearAlgebra.Single
             var matrix = new DenseMatrix(Count, 1);
             for (var i = 0; i < Data.Length; i++)
             {
-                matrix[i, 0] = Data[i];
+                matrix.At(i, 0, Data[i]);
             }
 
             return matrix;
@@ -196,7 +196,7 @@ namespace MathNet.Numerics.LinearAlgebra.Single
             var matrix = new DenseMatrix(1, Count);
             for (var i = 0; i < Data.Length; i++)
             {
-                matrix[0, i] = Data[i];
+                matrix.At(0, i, Data[i]);
             }
 
             return matrix;

src/Numerics/LinearAlgebra/Single/DiagonalMatrix.cs

@@ -945,7 +945,7 @@ namespace MathNet.Numerics.LinearAlgebra.Single
             result.Clear();
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
         }
 
@@ -1010,7 +1010,7 @@ namespace MathNet.Numerics.LinearAlgebra.Single
             result.Clear();
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
         }
 
@@ -1230,7 +1230,7 @@ namespace MathNet.Numerics.LinearAlgebra.Single
             // Copy the diagonal part into the result matrix.
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
 
             // Copy the lower matrix into the result matrix.
@@ -1238,7 +1238,7 @@ namespace MathNet.Numerics.LinearAlgebra.Single
             {
                 for (var j = 0; j < lower.ColumnCount; j++)
                 {
-                    result[i + RowCount, j] = lower[i, j];
+                    result.At(i + RowCount, j, lower.At(i, j));
                 }
             }
         }
@@ -1298,7 +1298,7 @@ namespace MathNet.Numerics.LinearAlgebra.Single
             // Copy the diagonal part into the result matrix.
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
 
             // Copy the lower matrix into the result matrix.
@@ -1306,7 +1306,7 @@ namespace MathNet.Numerics.LinearAlgebra.Single
             {
                 for (var j = 0; j < right.ColumnCount; j++)
                 {
-                    result[i, j + RowCount] = right[i, j];
+                    result.At(i, j + RowCount, right.At(i, j));
                 }
             }
         }
@@ -1362,7 +1362,7 @@ namespace MathNet.Numerics.LinearAlgebra.Single
             // Copy the diagonal part into the result matrix.
             for (var i = 0; i < _data.Length; i++)
             {
-                result[i, i] = _data[i];
+                result.At(i, i, _data[i]);
             }
 
             // Copy the lower matrix into the result matrix.

src/Numerics/LinearAlgebra/Single/Factorization/DenseEvd.cs

@@ -84,7 +84,7 @@ namespace MathNet.Numerics.LinearAlgebra.Single.Factorization
             {
                 for (var j = 0; j < order & IsSymmetric; j++)
                 {
-                    IsSymmetric &= matrix[i, j] == matrix[j, i];
+                    IsSymmetric &= matrix.At(i, j) == matrix.At(j, i);
                 }
             }
 
@@ -1143,7 +1143,7 @@ namespace MathNet.Numerics.LinearAlgebra.Single.Factorization
                             value += ((DenseMatrix)MatrixEv).Data[(i * order) + j] * tmp[i];
                         }
 
-                        result[j, k] = value;
+                        result.At(j, k, value);
                     }
                 }
             }

src/Numerics/LinearAlgebra/Single/Factorization/UserEvd.cs

@@ -84,7 +84,7 @@ namespace MathNet.Numerics.LinearAlgebra.Single.Factorization
             {
                 for (var j = 0; j < order & IsSymmetric; j++)
                 {
-                    IsSymmetric &= matrix[i, j] == matrix[j, i];
+                    IsSymmetric &= matrix.At(i, j) == matrix.At(j, i);
                 }
             }
 
@@ -1139,7 +1139,7 @@ namespace MathNet.Numerics.LinearAlgebra.Single.Factorization
                             value += MatrixEv.At(j, i) * tmp[i];
                         }
 
-                        result[j, k] = value;
+                        result.At(j, k, value);
                     }
                 }
             }

src/Numerics/LinearAlgebra/Single/Factorization/UserSvd.cs

@@ -850,7 +850,7 @@ namespace MathNet.Numerics.LinearAlgebra.Single.Factorization
                         value += MatrixVT.At(i, j) * tmp[i];
                     }
 
-                    result[j, k] = value;
+                    result.At(j, k, value);
                 }
             }
         }