| |  
 |  | 
 |  
 |  
 |  
 |  
 |  
 |  |  
 |  
 
 |  
 |  
 |  
 |  
 |  
 |  |  
 |  
 
 |  
 |  
 |  
 |  
 |  
 |  |  
 |  
 
 |  
 |  
 |  
 |  |   
 |  
 |  
 |  
 |  
 |  
 |  
 |  |  
 |  
 |  
 |  
 |  
 |  
 |  
 | | http://functions.wolfram.com/02.03.09.0009.01 | 
 |  
 |  
 |  
 |  
 |  
 |  |   
 |  
 |  |  |   
 |  
 |  
 |  
 |  
 |  
 |  
 |  |  
 |  
 |  
 |  
 |  
 |  
 |  
 | | Pi == Limit[(\[Alpha] n)/Sum[KroneckerDelta[Sign[Cos[k \[Alpha]]], 
      -Sign[Cos[(k + 1) \[Alpha]]]], {k, 0, n}], n -> Infinity] /; 
 0 <= \[Alpha] <= Pi | 
 |  
 |  
 |  
 |  
 |  
 |  |   
 |  
 |  
 |  
 |  
 |  
 |  
 |  |  
 |  
 |  
 |  
 |  
 |  
 |  
 | | Cell[BoxData[RowBox[List[RowBox[List["\[Pi]", "\[Equal]", RowBox[List["Limit", "[", RowBox[List[FractionBox[RowBox[List["\[Alpha]", " ", "n"]], RowBox[List[UnderoverscriptBox["\[Sum]", RowBox[List["k", "=", "0"]], "n"], RowBox[List["KroneckerDelta", "[", RowBox[List[RowBox[List["Sign", "[", RowBox[List["Cos", "[", RowBox[List["k", " ", "\[Alpha]"]], "]"]], "]"]], ",", RowBox[List["-", RowBox[List["Sign", "[", RowBox[List["Cos", "[", RowBox[List[RowBox[List["(", RowBox[List["k", "+", "1"]], ")"]], " ", "\[Alpha]"]], "]"]], "]"]]]]]], "]"]]]]], ",", RowBox[List["n", "\[Rule]", "\[Infinity]"]]]], "]"]]]], "/;", RowBox[List["0", "\[LessEqual]", "\[Alpha]", "\[LessEqual]", "\[Pi]"]]]]]] | 
 |  
 |  
 |  
 |  
 |  
 |  |   
 |  
 |  
 |  
 |  
 |  
 |  
 |  |  
 |  
 |  
 |  
 |  
 |  
 |  
 |  |  
 |  
 |  
 | | 
   <math xmlns='http://www.w3.org/1998/Math/MathML' mathematica:form='TraditionalForm' xmlns:mathematica='http://www.wolfram.com/XML/'>  <semantics>  <mrow>  <mrow>  <mi> π </mi>  <mo> ⩵ </mo>  <mrow>  <munder>  <mi> lim </mi>  <mrow>  <mi> n </mi>  <semantics>  <mo> → </mo>  <annotation encoding='Mathematica'> "\[Rule]" </annotation>  </semantics>  <mi> ∞ </mi>  </mrow>  </munder>  <mo> ⁢ </mo>  <mtext>   </mtext>  <mrow>  <mo> ( </mo>  <mrow>  <mi> α </mi>  <mo> ⁢ </mo>  <mrow>  <mi> n </mi>  <mo> / </mo>  <mrow>  <mo> ( </mo>  <mrow>  <munderover>  <mo> ∑ </mo>  <mrow>  <mi> k </mi>  <mo> = </mo>  <mn> 0 </mn>  </mrow>  <mi> n </mi>  </munderover>  <msub>  <semantics>  <mi> δ </mi>  <annotation-xml encoding='MathML-Content'>  <ci> KroneckerDelta </ci>  </annotation-xml>  </semantics>  <mrow>  <mrow>  <mi> sgn </mi>  <mo> ⁡ </mo>  <mo> ( </mo>  <mrow>  <mi> cos </mi>  <mo> ⁡ </mo>  <mo> ( </mo>  <mrow>  <mi> k </mi>  <mo> ⁢ </mo>  <mi> α </mi>  </mrow>  <mo> ) </mo>  </mrow>  <mo> ) </mo>  </mrow>  <mo> , </mo>  <mrow>  <mo> - </mo>  <mrow>  <mi> sgn </mi>  <mo> ⁡ </mo>  <mo> ( </mo>  <mrow>  <mi> cos </mi>  <mo> ⁡ </mo>  <mo> ( </mo>  <mrow>  <mrow>  <mo> ( </mo>  <mrow>  <mi> k </mi>  <mo> + </mo>  <mn> 1 </mn>  </mrow>  <mo> ) </mo>  </mrow>  <mo> ⁢ </mo>  <mi> α </mi>  </mrow>  <mo> ) </mo>  </mrow>  <mo> ) </mo>  </mrow>  </mrow>  </mrow>  </msub>  </mrow>  <mo> ) </mo>  </mrow>  </mrow>  </mrow>  <mo> ) </mo>  </mrow>  </mrow>  </mrow>  <mo> /; </mo>  <mrow>  <mn> 0 </mn>  <mo> ≤ </mo>  <mi> α </mi>  <mo> ≤ </mo>  <mi> π </mi>  </mrow>  </mrow>  <annotation-xml encoding='MathML-Content'>  <apply>  <ci> Condition </ci>  <apply>  <eq />  <pi />  <apply>  <limit />  <bvar>  <ci> n </ci>  </bvar>  <condition>  <apply>  <tendsto />  <ci> n </ci>  <infinity />  </apply>  </condition>  <apply>  <times />  <ci> α </ci>  <apply>  <times />  <ci> n </ci>  <apply>  <power />  <apply>  <sum />  <bvar>  <ci> k </ci>  </bvar>  <lowlimit>  <cn type='integer'> 0 </cn>  </lowlimit>  <uplimit>  <ci> n </ci>  </uplimit>  <apply>  <ci> KroneckerDelta </ci>  <apply>  <ci> Sign </ci>  <apply>  <cos />  <apply>  <times />  <ci> k </ci>  <ci> α </ci>  </apply>  </apply>  </apply>  <apply>  <times />  <cn type='integer'> -1 </cn>  <apply>  <ci> Sign </ci>  <apply>  <cos />  <apply>  <times />  <apply>  <plus />  <ci> k </ci>  <cn type='integer'> 1 </cn>  </apply>  <ci> α </ci>  </apply>  </apply>  </apply>  </apply>  </apply>  </apply>  <cn type='integer'> -1 </cn>  </apply>  </apply>  </apply>  </apply>  </apply>  <apply>  <leq />  <cn type='integer'> 0 </cn>  <ci> α </ci>  <pi />  </apply>  </apply>  </annotation-xml>  </semantics>  </math> 
   | 
 |  
 |  
 |  
 |  
 |  
 |  |  
 |  |  
 |  
 |  
 |  |  
 |  |  
 |  |  
 |  
 |  
 |  |  
 | | Cell[BoxData[RowBox[List[RowBox[List["HoldPattern", "[", "\[Pi]", "]"]], "\[RuleDelayed]", RowBox[List[RowBox[List["Limit", "[", RowBox[List[FractionBox[RowBox[List["\[Alpha]", " ", "n"]], RowBox[List[UnderoverscriptBox["\[Sum]", RowBox[List["k", "=", "0"]], "n"], RowBox[List["KroneckerDelta", "[", RowBox[List[RowBox[List["Sign", "[", RowBox[List["Cos", "[", RowBox[List["k", " ", "\[Alpha]"]], "]"]], "]"]], ",", RowBox[List["-", RowBox[List["Sign", "[", RowBox[List["Cos", "[", RowBox[List[RowBox[List["(", RowBox[List["k", "+", "1"]], ")"]], " ", "\[Alpha]"]], "]"]], "]"]]]]]], "]"]]]]], ",", RowBox[List["n", "\[Rule]", "\[Infinity]"]]]], "]"]], "/;", RowBox[List["0", "\[LessEqual]", "\[Alpha]", "\[LessEqual]", "\[Pi]"]]]]]]]] | 
 |  
 |   
 |  
 |  
 | |   
 |  
 |  
 |  
 |  
 |  
 |  
 | | Date Added to functions.wolfram.com (modification date) | 
 |  
 |  
 |  
 |  
 |  
 |  
 |  
 |  |  
 |   
 |  
 |  
 |  |  | 
 
 
 | 
 |