Performance

examples/src/org/ejml/example/PolynomialFit.java

@@ -157,8 +157,8 @@ private void removeObservation( int index ) {
         final double d[] = y.data;
 
         // shift
-        for( int i = index; i < N; i++ ) {
-            d[i] = d[i+1];
+        if (N - index >= 0) {
+            System.arraycopy(d, index + 1, d, index, N - index);
         }
         y.numRows--;
     }

main/ejml-core/generate/org/ejml/data/GenerateMatrixFixedNxN.java

@@ -150,9 +150,9 @@ private void printClassParam( int dimen ) {
     }
 
     private void printFunctionParam( int spaces, int dimen ) {
-        String s = "";
+        StringBuilder s = new StringBuilder();
         for (int i = 0; i < spaces; i++) {
-            s += " ";
+            s.append(" ");
         }
         for( int y = 1; y <= dimen; y++ ) {
             if( y == 1 )

main/ejml-core/src/org/ejml/data/DMatrixSparseTriplet.java

@@ -304,8 +304,8 @@ public void remove(int row, int col) {
         if( where >= 0 ) {
 
             nz_length -= 1;
-            for (int i = where; i < nz_length; i++) {
-                nz_value.data[i] = nz_value.data[i+1];
+            if (nz_length - where >= 0) {
+                System.arraycopy(nz_value.data, where + 1, nz_value.data, where, nz_length - where);
             }
             int end = nz_length*2;
             for (int i = where*2; i < end; i += 2) {

main/ejml-ddense/generate/org/ejml/dense/fixed/GenerateFixedFeatures.java

@@ -91,13 +91,13 @@ private void hasUncountable(int dimen ){
         out.print("    public static boolean hasUncountable("+nameMatrix+" a ) {\n");
 
         for( int y = 1; y <= dimen; y++ ) {
-            String row = "";
+            StringBuilder row = new StringBuilder();
 
             for( int x = 1; x <= dimen; x++ ) {
                 String n = y+""+x;
                 if( x > 1 )
-                    row += "+ ";
-                row += "a.a"+n;
+                    row.append("+ ");
+                row.append("a.a").append(n);
             }
             out.print("        if( UtilEjml.isUncountable("+row+"))\n"+
                     "            return true;\n");

main/ejml-ddense/src/org/ejml/dense/row/decomposition/hessenberg/TridiagonalDecompositionHouseholder_DDRM.java

@@ -133,8 +133,8 @@ public DMatrixRMaj getQ(@Nullable DMatrixRMaj Q , boolean transposed ) {
         if( transposed ) {
             for( int j = N-2; j >= 0; j-- ) {
                 w[j+1] = 1;
-                for( int i = j+2; i < N; i++ ) {
-                    w[i] = QT.data[j*N+i];
+                if (N - j + 2 >= 0) {
+                    System.arraycopy(QT.data, j * N + j + 2, w, j + 2, N - j + 2);
                 }
                 QrHelperFunctions_DDRM.rank1UpdateMultL(Q, w, gammas[j + 1], j + 1, j + 1, N);
             }

main/ejml-ddense/src/org/ejml/dense/row/misc/DeterminantFromMinor_DDRM.java

@@ -197,8 +197,8 @@ private int openRemove( int where ) {
 
     private void openAdd( int where, int val )
     {
-        for( int i = numOpen; i > where; i-- ) {
-            open[i] = open[i-1];
+        if (numOpen - where >= 0) {
+            System.arraycopy(open, where, open, where + 1, numOpen - where);
         }
         numOpen++;
         open[where] = val;

main/ejml-experimental/src/org/ejml/dense/row/decomposition/svd/SvdImplicitQrDecompose_Ultimate.java

@@ -135,8 +135,8 @@ public DMatrixRMaj getW(@Nullable DMatrixRMaj W ) {
             W.zero();
         }
 
-        for( int i = 0; i < numSingular; i++ ) {
-            W.data[i*W.numCols+i] = singularValues[i];
+        if (numSingular >= 0) {
+            System.arraycopy(singularValues, 0, W.data, 0 * W.numCols + 0, numSingular);
         }
 
         return W;

main/ejml-experimental/src/org/ejml/dense/row/decomposition/svd/SvdImplicitQrDecompose_UltimateS.java

@@ -135,8 +135,8 @@ public DMatrixRMaj getW(@Nullable DMatrixRMaj W ) {
             W.zero();
         }
 
-        for( int i = 0; i < numSingular; i++ ) {
-            W.data[i*W.numCols+i] = singularValues[i];
+        if (numSingular >= 0) {
+            System.arraycopy(singularValues, 0, W.data, 0 * W.numCols + 0, numSingular);
         }
 
         return W;

main/ejml-simple/src/org/ejml/equation/TokenList.java

@@ -236,13 +236,13 @@ public void insertAfter(Token before, TokenList list ) {
      */
     @Override
     public String toString() {
-        String ret = "";
+        StringBuilder ret = new StringBuilder();
         Token t = first;
         while( t != null ) {
-            ret += t +" ";
+            ret.append(t).append(" ");
             t = t.next;
         }
-        return ret;
+        return ret.toString();
     }
 
     /**