Merge branch 'feature/49-rms-function' into develop

Fixes #49

Author: delphidabbler

collection/702.dat

@@ -0,0 +1,11 @@
+function RMS(const A: array of Double): Double; overload;
+var
+  Squares: array of Double;
+  Idx: Integer;
+begin
+  System.SetLength(Squares, System.Length(A));
+  for Idx := 0 to Pred(System.Length(A)) do
+    Squares[Idx] := A[Idx] * A[Idx];
+  // Note: ArithmeticMean raises exception if A is empty
+  Result := Math.Power(ArithmeticMean(Squares), 0.5);
+end;

collection/703.dat

@@ -0,0 +1,16 @@
+function RMS(const A: array of Integer): Double; overload;
+var
+  Squares: array of Double;
+  Idx: Integer;
+  Elem: Double;
+begin
+  System.SetLength(Squares, System.Length(A));
+  for Idx := 0 to Pred(System.Length(A)) do
+  begin
+    // convert Integer to Double before squaring to reduce change of overflow
+    Elem := A[Idx];
+    Squares[Idx] := Elem * Elem;
+  end;
+  // Note: ArithmeticMean raises exception if A is empty
+  Result := Math.Power(ArithmeticMean(Squares), 0.5);
+end;

collection/maths.ini

@@ -2387,3 +2387,31 @@ AdvancedTest.URL="https://github.com/delphidabbler/code-snippets/tree/master/tes
 Snip=701.dat
 DelphiXE=Y
 Delphi12A=Y
+
+[RMS_Double]
+DisplayName="RMS (Double overload)"
+DescEx="<p>Calculates the root mean square of the elements of <var>Double</var> floating point array <var>A</var>.</p><p>Raises <var>EArgumentException</var> if <var>A</var> is empty.</p>"
+Kind=routine
+Units=SysUtils,Math
+Depends=ArithmeticMean_Double
+SeeAlso=RMS_Integer
+TestInfo=advanced
+AdvancedTest.Level=unit-tests
+AdvancedTest.URL="https://github.com/delphidabbler/code-snippets/tree/master/tests/Cat-Maths"
+Snip=702.dat
+DelphiXE=Y
+Delphi12A=Y
+
+[RMS_Integer]
+DisplayName="RMS (Integer overload)"
+DescEx="<p>Calculates the root mean square of the elements of <var>Integer</var> array <var>A</var>.</p><p>Raises <var>EArgumentException</var> if <var>A</var> is empty.</p>"
+Kind=routine
+Units=SysUtils,Math
+Depends=ArithmeticMean_Double
+SeeAlso=RMS_Double
+TestInfo=advanced
+AdvancedTest.Level=unit-tests
+AdvancedTest.URL="https://github.com/delphidabbler/code-snippets/tree/master/tests/Cat-Maths"
+Snip=703.dat
+DelphiXE=Y
+Delphi12A=Y

tests/Cat-Maths/TestUMathsCatSnippets.pas

@@ -84,6 +84,8 @@   TestMathsCatSnippets = class(TTestCase)
     procedure TestHasMode_ExceptSingleElementArray;
     procedure TestModeCount_ExceptEmptyArray;
     procedure TestModeCount_ExceptSingleElementArray;
+    procedure TestRMS_Double_ExceptEmptyArray;
+    procedure TestRMS_Integer_ExceptEmptyArray;
     function EqualArrays(const Left, Right: TBytes): Boolean; overload;
     function EqualArrays(const Left, Right: array of Integer): Boolean;
       overload;
@@ -187,6 +189,8 @@   TestMathsCatSnippets = class(TTestCase)
     procedure TestModeAlt;
     procedure TestHasMode;
     procedure TestModeCount;
+    procedure TestRMS_Double;
+    procedure TestRMS_Integer;
   end;
 
 implementation
@@ -2418,6 +2422,58 @@ procedure TestMathsCatSnippets.TestResizeRect_B;
   CheckEquals(-4, RectHeight(R), '3: RectHeight');
 end;
 
+procedure TestMathsCatSnippets.TestRMS_Double;
+const
+  Fudge = 0.0001;
+  A: array[1..4] of Double = (23.45, 35.786, 87326.948, 13);
+  B: array[1..8] of Double = (-19.0, 27.890, -42.83729, 56.73829, 100.0, -100.0, 0.0, 666.6);
+  C: array[1..3] of Double = (0.0, 0.0, 0.0);
+  D: array[1..1] of Double = (2345.67889);
+  E: array[1..2] of Double = (-999.99, +999.99);
+begin
+  // Some expected results from https://miniwebtool.com/root-mean-square-calculator/
+  CheckEquals(43663.47973, RMS(A), Fudge, 'A');
+  CheckEquals(242.5254314, RMS(B), Fudge, 'B');
+  CheckEquals(0.0, RMS(C), Fudge, 'C');
+  CheckEquals(2345.67889, RMS(D), Fudge, 'D');
+  CheckEquals(999.99, RMS(E), Fudge, 'E');
+  CheckException(TestRMS_Double_ExceptEmptyArray, EArgumentException, 'Empty array');
+end;
+
+procedure TestMathsCatSnippets.TestRMS_Double_ExceptEmptyArray;
+var
+  A: array of Double;
+begin
+  SetLength(A, 0);
+  RMS(A);
+end;
+
+procedure TestMathsCatSnippets.TestRMS_Integer;
+const
+  Fudge = 0.0001;
+  A: array[1..4] of Integer = (23, 36, 87327, 13);
+  B: array[1..8] of Integer = (-19, 28, -43, 57, 100, -100, 0, 666);
+  C: array[1..3] of Integer = (0, 0, 0);
+  D: array[1..1] of Integer = (2346);
+  E: array[1..2] of Integer = (-999, +999);
+begin
+  // Some expected results from https://miniwebtool.com/root-mean-square-calculator/
+  CheckEquals(43663.505708428864, RMS(A), Fudge, 'A');
+  CheckEquals(242.3321584, RMS(B), Fudge, 'B');
+  CheckEquals(0.0, RMS(C), Fudge, 'C');
+  CheckEquals(2346.0, RMS(D), Fudge, 'D');
+  CheckEquals(999.0, RMS(E), Fudge, 'E');
+  CheckException(TestRMS_Integer_ExceptEmptyArray, EArgumentException, 'Empty array');
+end;
+
+procedure TestMathsCatSnippets.TestRMS_Integer_ExceptEmptyArray;
+var
+  A: array of Integer;
+begin
+  SetLength(A, 0);
+  RMS(A);
+end;
+
 procedure TestMathsCatSnippets.TestSoftMax;
 
   function ArraysEqual(const Left, Right: array of Double): Boolean;

tests/Cat-Maths/UMathsCatSnippets.pas

@@ -6,7 +6,7 @@
  * The unit is copyright © 2005-2025 by Peter Johnson & Contributors and is
  * licensed under the MIT License (https://opensource.org/licenses/MIT).
  * 
- * Generated on : Fri, 17 Jan 2025 09:41:35 GMT.
+ * Generated on : Sat, 18 Jan 2025 09:49:49 GMT.
  * Generated by : DelphiDabbler CodeSnip Release 4.24.0.
  * 
  * The latest version of CodeSnip is available from the CodeSnip GitHub project
@@ -669,6 +669,19 @@ function ReverseNumber(AValue: Int64): Int64;
 }
 function ReverseNumberR(AValue: Int64): Int64;
 
+{
+  Calculates the root mean square of the elements of Double floating point array
+  A.
+  Raises EArgumentException if A is empty.
+}
+function RMS(const A: array of Double): Double; overload;
+
+{
+  Calculates the root mean square of the elements of Integer array A.
+  Raises EArgumentException if A is empty.
+}
+function RMS(const A: array of Integer): Double; overload;
+
 {
   Performs an arithmetic right shift operation on the given value and returns
   the result. Value is shifted right by Shift bits.
@@ -2838,6 +2851,44 @@ function ReverseNumberR(AValue: Int64): Int64;
       + ReverseNumberR(AValue div 10)
 end;
 
+{
+  Calculates the root mean square of the elements of Double floating point array
+  A.
+  Raises EArgumentException if A is empty.
+}
+function RMS(const A: array of Double): Double; overload;
+var
+  Squares: array of Double;
+  Idx: Integer;
+begin
+  System.SetLength(Squares, System.Length(A));
+  for Idx := 0 to Pred(System.Length(A)) do
+    Squares[Idx] := A[Idx] * A[Idx];
+  // Note: ArithmeticMean raises exception if A is empty
+  Result := Math.Power(ArithmeticMean(Squares), 0.5);
+end;
+
+{
+  Calculates the root mean square of the elements of Integer array A.
+  Raises EArgumentException if A is empty.
+}
+function RMS(const A: array of Integer): Double; overload;
+var
+  Squares: array of Double;
+  Idx: Integer;
+  Elem: Double;
+begin
+  System.SetLength(Squares, System.Length(A));
+  for Idx := 0 to Pred(System.Length(A)) do
+  begin
+    // convert Integer to Double before squaring to reduce change of overflow
+    Elem := A[Idx];
+    Squares[Idx] := Elem * Elem;
+  end;
+  // Note: ArithmeticMean raises exception if A is empty
+  Result := Math.Power(ArithmeticMean(Squares), 0.5);
+end;
+
 {
   Performs an arithmetic right shift operation on the given value and returns
   the result. Value is shifted right by Shift bits.