这是一个很好的例子,您可以充分利用广播。看起来您想要 和 之间的笛卡尔积x
,nu
其中行由 的值填充,nu
列是x
。这正是广播可以做的——你只需要重塑x
它,使它成为跨多列的单行:
julia> using SpecialFunctions
julia> x = 1.0:0.1:2.0
1.0:0.1:2.0
julia> nu = 0.5 + (0:500)
0.5:1.0:500.5
# this shows how broadcast works — these are the arguments and their location in the matrix
julia> tuple.(nu, reshape(x, 1, :))
501×11 Array{Tuple{Float64,Float64},2}:
(0.5, 1.0) (0.5, 1.1) … (0.5, 1.9) (0.5, 2.0)
(1.5, 1.0) (1.5, 1.1) (1.5, 1.9) (1.5, 2.0)
(2.5, 1.0) (2.5, 1.1) (2.5, 1.9) (2.5, 2.0)
(3.5, 1.0) (3.5, 1.1) (3.5, 1.9) (3.5, 2.0)
⋮ ⋱ ⋮
(497.5, 1.0) (497.5, 1.1) (497.5, 1.9) (497.5, 2.0)
(498.5, 1.0) (498.5, 1.1) (498.5, 1.9) (498.5, 2.0)
(499.5, 1.0) (499.5, 1.1) (499.5, 1.9) (499.5, 2.0)
(500.5, 1.0) (500.5, 1.1) … (500.5, 1.9) (500.5, 2.0)
julia> bj = besselj.(nu,reshape(x, 1, :)).*sqrt.(pi/2*reshape(x, 1, :))
501×11 Array{Float64,2}:
0.841471 0.891207 0.932039 … 0.9463 0.909297
0.301169 0.356592 0.414341 0.821342 0.870796
0.0620351 0.0813173 0.103815 0.350556 0.396896
0.00900658 0.0130319 0.0182194 0.101174 0.121444
⋮ ⋱ ⋮
0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 … 0.0 0.0