More code ported

LinearAlgebra/Matrix.cpp

@@ -194,6 +194,13 @@ Matrix2 Matrix2::operator+=(const Matrix2& v) {
   return *this;
 }
 
+Matrix2 Matrix2::operator-(const Matrix2& v) const {
+  Matrix2 r = Matrix2(this->nRows, this->nCols);
+  for (int ix = 0; ix < r.nValues; ix++)
+    r.data[ix] = this->data[ix] - v.data[ix];
+  return r;
+}
+
 Matrix2 LinearAlgebra::Matrix2::operator*(const Matrix2& B) const {
   Matrix2 r = Matrix2(this->nRows, B.nCols);
 
@@ -223,6 +230,23 @@ Matrix2 LinearAlgebra::Matrix2::operator*(const Matrix2& B) const {
   return r;
 }
 
+Matrix2 Matrix2::GetRows(int from, int to) {
+  if (from < 0 || to >= this->nRows)
+    std::cerr << "Slice index out of range." << "std::endl";
+
+  Matrix2 result = Matrix2(to - from, this->nCols);
+  int resultRowIx = 0;
+  for (int rowIx = from; rowIx < to; rowIx++) {
+    for (int colIx = 0; colIx < this->nCols; colIx++)
+      result.data[resultRowIx * result.nCols + colIx] =
+          this->data[rowIx * this->nCols + colIx];
+
+    resultRowIx++;
+  }
+
+  return result;
+}
+
 Matrix2 Matrix2::Slice(int rowStart, int rowStop, int colStart, int colStop) {
   Matrix2 r = Matrix2(rowStop - rowStart, colStop - colStart);
 
@@ -259,6 +283,59 @@ void Matrix2::UpdateSlice(int rowStart,
   }
 }
 
+Matrix2 Matrix2::Inverse() {
+  int n = this->nRows;
+  // // Create an identity matrix of the same size as the original matrix
+  Matrix2 augmentedMatrix(n, 2 * n);
+  for (int i = 0; i < n; i++) {
+    for (int j = 0; j < n; j++) {
+      augmentedMatrix.data[i * this->nCols + j] = this->data[i, j];
+      augmentedMatrix.data[i * this->nCols + (j + n)] =
+          (i == j) ? 1 : 0;  // identity matrix;
+    }
+  }
+
+  // Perform Gaussian elimination
+  for (int i = 0; i < n; i++) {
+    // Find the pivot row
+    float pivot = augmentedMatrix.data[i * augmentedMatrix.nCols + i];
+    if (abs(pivot) < 1e-10)  // Check for singular matrix
+      std::cerr << "Matrix is singular and cannot be inverted." << std::endl;
+
+    // Normalize the pivot row
+    for (int j = 0; j < 2 * n; j++)
+      augmentedMatrix.data[i * augmentedMatrix.nCols + j] /= pivot;
+
+    // Eliminate the column below the pivot
+    for (int j = i + 1; j < n; j++) {
+      float factor = augmentedMatrix.data[j * augmentedMatrix.nCols + i];
+      for (int k = 0; k < 2 * n; k++)
+        augmentedMatrix.data[j * augmentedMatrix.nCols + k] -=
+            factor * augmentedMatrix.data[i * augmentedMatrix.nCols + k];
+    }
+  }
+
+  // Back substitution
+  for (int i = n - 1; i >= 0; i--) {
+    // Eliminate the column above the pivot
+    for (int j = i - 1; j >= 0; j--) {
+      float factor = augmentedMatrix.data[j * augmentedMatrix.nCols + i];
+      for (int k = 0; k < 2 * n; k++)
+        augmentedMatrix.data[j * augmentedMatrix.nCols + k] -=
+            factor * augmentedMatrix.data[i * augmentedMatrix.nCols + k];
+    }
+  }
+
+  // Extract the inverse matrix from the augmented matrix
+  Matrix2 inverse(n, n);
+  for (int i = 0; i < n; i++) {
+    for (int j = 0; j < n; j++)
+      inverse.data[i * inverse.nCols + j] =
+          augmentedMatrix.data[i * augmentedMatrix.nCols + j + n];
+  }
+  return inverse;
+}
+
 Matrix2 Matrix2::DeleteRows(int rowStart, int rowStop) {
   Matrix2 r = Matrix2(this->nRows - (rowStop - rowStart), this->nCols);
 

LinearAlgebra/Matrix.h

@@ -80,6 +80,8 @@ class Matrix2 {
   Matrix2 operator+(const Matrix2& v) const;
   Matrix2 operator+=(const Matrix2& v);
 
+  Matrix2 operator-(const Matrix2& v) const;
+
   Matrix2 operator*(const Matrix2& m) const;
   friend Matrix2 operator*(const Matrix2& m, float f) {
     Matrix2 r = Matrix2(m.nRows, m.nCols);
@@ -117,22 +119,9 @@ class Matrix2 {
     return r;
   }
 
-  Matrix2 GetRows(int from, int to) {
+  Matrix2 GetRows(int from, int to);
-    if (from < 0 || to >= this->nRows)
-      std::cerr << "Slice index out of range." << "std::endl";
-
-    Matrix2 result = Matrix2(to-from, this->nCols);
-    int resultRowIx = 0;
-    for (int rowIx = from; rowIx < to; rowIx++) {
-      for (int colIx = 0; colIx < this->nCols; colIx++)
-        result.data[resultRowIx * result.nCols + colIx] = this->data[rowIx * this->nCols + colIx];
-
-      resultRowIx++;
-    }
-
-    return result;
-  }
 
+  void SetRow(int rowIx, Matrix1 source) {}
   Matrix2 Slice(int rawStart, int rowStop, int colStart, int colStop);
 
   void UpdateSlice(int rowStart,
@@ -141,6 +130,8 @@ class Matrix2 {
                    int colStop,
                    const Matrix2& m) const;
 
+  Matrix2 Inverse();
+
   Matrix2 DeleteRows(int rowStart, int rowStop);
   Matrix2 DeleteColumns(int colStart, int colStop);