Julia DSP：离散信号的卷积

Question

这里是problem。我想为两个简单信号 x[n]=0.2^n*u[n] 和 h[n]=u[n+2] 写一个卷积，以获得一些 n 值。我是这样实现的：

using Plots, DSP

x(n) = if n<0 0 else 0.2^n end
h(n) = if n<-2 0 else 1 end

n = -10:10
conv(h.(n),x.(n))

没用。这是错误：

`float` not defined on abstractly-typed arrays; please convert to a more specific type

知道我该如何解决吗？

Answer 1

我运行新的 REPL 会话没问题：

julia> using Plots, DSP
[ Info: Precompiling Plots [91a5bcdd-55d7-5caf-9e0b-520d859cae80]
[ Info: Precompiling DSP [717857b8-e6f2-59f4-9121-6e50c889abd2]
        
julia> x(n) = if n<0 0 else 2^n end
x (generic function with 1 method)

julia> h(n) = if n<-2 0 else 1 end
h (generic function with 1 method)

julia> n = -10:10
-10:10

julia> conv(h.(n),x.(n))
41-element Array{Int64,1}:
    0
    0
  
 (etc)
 
 1984
 1920
 1792
 1536
 1024

julia> plot(conv(h.(n),x.(n)))
(plots ok)

如果将 2 in 2^n 更改为浮点数，则需要指定 Float64:

julia>  x(n) = if n<0 0 else  0.2^n end
x (generic function with 1 method)

julia> conv(h.(n),Float64.(x.(n)))
41-element Array{Float64,1}:
  0.0
  8.458842092382145e-17
  2.5376526277146434e-16
  4.229421046191072e-17
  2.1147105230955362e-16
       
   (etc)
   
  7.997440000004915e-5
  1.597440000003685e-5
  3.1744000002024485e-6
  6.144000000924524e-7
  1.0240000015600833e-7

Julia DSP：离散信号的卷积

Julia DSP: Convolution of discrete signals

signal-processing

convolution

julia