1.
f(t)为偶函数—对称于纵轴
f(t)=f(−t)
an=T2∫−2T2Tf(t)cos(nΩt)dt
bn=T2∫−2T2Tf(t)sin(nΩt)dt
an=2∗T2∫−2T2Tf(t)cos(nΩt)dt
bn=0展开为余弦函数。
2.
f(t)为奇函数的时候
f(t)=−f(−t)
an=T2∫−2T2Tf(t)cos(nΩt)dt
bn=T2∫−2T2Tf(t)sin(nΩt)dt
an=2∗T2∫−2T2Tf(t)cos(nΩt)
易得到
an=0
3.
f(t)为奇 谐函数---------
f(t)=−f(t±T/2)
其傅里叶级数中只含有奇次谐波分量,而不含偶次谐波分量,即:
a0=a2=.....=b2=b4=...=0
4.
f(t)为偶谐函数---------
f(t)=f(t±T/2)
其傅里叶级数之中只含偶次谐波分量,而不含奇次谐波分量:即
a1=a3=...=b1=b3=...=0