sinc函数
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sinA:sinB:sinC=2:3:4a:b:c=2:3:4(4K)²=(2k)²+(3K)²-2*2k*3k*cosCcosC=-1/4sinC=√15/4
t=-50:1:50;y=sin(pi*t/8)./(pi*t/8);xlabel('t','FontSize',20);ylabel('p','
1.假设a/sinA=b/sinB=c/sinC=2R那么sinA=a/2RsinB=b/2RsinC=c/2R因为(sinA)平方=(sinB)平方+sinC(sinB+sinC)所以(a/2R)^
C=180-(A+B)而sin(180-x)=sinx所以sinC=sin[180-(A+B)]=sin(A+B)
SINCSin(pi*x)/(pi*x)function.
就是转置了一下,行向量变成列向量,比如:>>t=0:0.1:10;>>size(sinc(t))ans=1101>>size(sinc(t'))ans=1011>>size(sinc(t.'))ans
证明:设sinA/a=sinB/b=sinC/c=k,则sinA=ak,sinB=bk,sinC=ck,sinA/(sinB+sinC)+sinB/(sinA+sinC)+sinC(sinA+sinB
fork=1:length(y)f=@(x)y(k)*x-sin(x);ezplot(f);%画图,观察函数零点在x0(k)附近z(k)=fzero(f,x0(k));%调用fzero函数找零点end
证:∵△ABC为锐角三角形,∴A+B>90°得A>90°-B∴sinA>sin(90°-B)=cosB,即sinA>cosB,同理可得sinB>cosC,sinC>cosA上面三式相加:sinA+si
s为三角形半周长,r为三角形内切圆半径,R为三角形外接圆半径sinA+sinB+sinC=s/RcosA+cosB+cosC=(r+R)/Ry=s/(r+R)2R+2r>s也就是内切圆直径加外接圆直径
tan(A-B)=(tanA-tanB)/(1+tanA*tanB)tan(A-B)/tanA+sin²C/sin²A=1左右移项得1-[(tanA-tanB)/(1+tanA*t
tan(A-B)=(tanA-tanB)/(1+tanA*tanB)tan(A-B)/tanA+sin²C/sin²A=1左右移项得1-[(tanA-tanB)/(1+tanA*t
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ect(x)
可见,你给的代码里,画的是Sa(t).
c=40度(~40.48884564)
sinc函数有两个定义,有时区分为归一化sinc函数和非归一化的sinc函数.它们都是正弦函数和单调递减函数1/x的乘积:sinc(x)=sin(pi*x)/(pi*x);归一化rectxsinc函数
这样考虑:cosA/cosB=b/a=sinB/sinA,所以有sinAcosA-sinBcosB=1/2(sin2A-sin2B)=0所以由和差化积:sin(A-B)cos(A+B)=0,这就说明要
∵acosA+bcosB=ccosC∴sinAcosA+sinBcosB=sinCcosC∴sin2A+sin2B=sin2C=sin(2π-2A-2B)=-sin(2A+2B)∴0=sin2A+si
试根据FT的对称性,利用矩形脉冲信号的傅里叶变换来求解Sa函数的傅里叶变换,具体请参考:http://comic.sjtu.edu.cn/thucs/GD_jsj_004b/text/chap2/se