作业帮matlab num=[4];den=[1 2 1]; margin(num,den),grid; w=0.1:1000; [mag,phase,w]=bode(num,den);mag(1)mag(1.5)输出：mag（1）=3.9996但是mag（1.5）出了问题,如下：Subscript indices must either be real positive integers or logicals.只要mag（
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![matlab num=[4];den=[1 2 1]; margin(num,den),grid; w=0.1:1000; [mag,phase,w]=bode(num,den);mag(1)mag(1.5)输出：mag（1）=3.9996但是mag（1.5）出了问题,如下：Subscript indices must either be real positive integers or logicals.只要mag（](/uploads/image/z/6995681-17-1.jpg?t=matlab+num%3D%5B4%5D%3Bden%3D%5B1+2+1%5D%3B+margin%28num%2Cden%29%2Cgrid%3B+w%3D0.1%3A1000%3B+%5Bmag%2Cphase%2Cw%5D%3Dbode%28num%2Cden%29%3Bmag%281%29mag%281.5%29%E8%BE%93%E5%87%BA%EF%BC%9Amag%EF%BC%881%EF%BC%89%3D3.9996%E4%BD%86%E6%98%AFmag%EF%BC%881.5%EF%BC%89%E5%87%BA%E4%BA%86%E9%97%AE%E9%A2%98%2C%E5%A6%82%E4%B8%8B%EF%BC%9ASubscript+indices+must+either+be+real+positive+integers+or+logicals.%E5%8F%AA%E8%A6%81mag%EF%BC%88)
matlab num=[4];den=[1 2 1]; margin(num,den),grid; w=0.1:1000; [mag,phase,w]=bode(num,den);mag(1)mag(1.5)输出：mag（1）=3.9996但是mag（1.5）出了问题,如下：Subscript indices must either be real positive integers or logicals.只要mag（
matlab num=[4];den=[1 2 1]; margin(num,den),grid; w=0.1:1000; [mag,phase,w]=bode(num,den);
mag(1)
mag(1.5)
输出：mag（1）=3.9996
但是mag（1.5）出了问题,如下：
Subscript indices must either be real positive integers or logicals.
只要mag（）括号中为整数就没问题,为什么小数就是不行呢?
matlab num=[4];den=[1 2 1]; margin(num,den),grid; w=0.1:1000; [mag,phase,w]=bode(num,den);mag(1)mag(1.5)输出：mag（1）=3.9996但是mag（1.5）出了问题,如下：Subscript indices must either be real positive integers or logicals.只要mag（
mag(1) 并不代表w=1时mag的值,而是得到结果向量mag的第一个元素,对应输出w的第一个元素.
所以mag(1.5)的意思是mag中第1.5个元素,而元素的序数显然不能是小数,所以出现错误.