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小弟想寫convolution的matlab程式
x1信號長度999，x2信號長度500。
聽說在matlab中，用向量代替迴圈可以增加速度
但是我做出來卻比較慢QQ
不知為何?

迴圈版本:
function y = myconv(x1, x2)
y=zeros(1,1499);
for n=2:1:501
    for k=1:1:n-1
        y(n)=y(n)+g(k)*h(n-k);
    end
end
for n=502:1:1000
    k=n-500;
    count=0;
    while  count<500
        y(n)=y(n)+g(k)*h(n-k);
        k=k+1;
        count=count+1;
    end
end
for n=1001:1:1499
    k=n-500;
    while  k<=999
        y(n)=y(n)+g(k)*h(n-k);
        k=k+1;
    end
end

向量化版本:(內層迴圈向量化)
function y = myconv(x1, x2)
y=zeros(1,1499);
for n=2:1499
    if(n<502)
        k=1:n-1;
        y(n)=sum(x1(k).*x2(n-k));
    elseif(n<1001)
         k=n-500:n-1;
         y(n)=sum(x1(k).*x2(n-k));
    else
        k=n-500:999;
        y(n)=sum(x1(k).*x2(n-k));
    end
end

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