⑩天掌 Teaching Plan on Advanced Mathematics o 、三角级数三角函数系的正交性 1.三角级数 ∫(t)=A+∑Asin(mof+qn)谐波分析 =1 A0+2(A, sin (p, cos not+ An, cos (n sin nat) A0=Ao, a,=A, sin(m, b,=A, cos n5 ot=x au+∑( a. cos nx+ h sinx)三角级数 2 tianjin polytechnic dmivendityTianjin Polytechnic University Teaching Plan on Advanced Mathematics 一、三角级数 三角函数系的正交性 = +   +   =1 0 ( ) sin( ) n n n f t A A n t 1.三角级数 谐波分析 = +    +    =1 0 ( sin cos cos sin ) n n n n n A A n t A n t +  +  =1 0 ( cos sin ) 2 n an nx bn nx a , 2 0 0 A a 令 = sin , n An n a =  cos , n An n b =  t = x, 三角级数