Question

我有这个代码，我想运行它，但是我遇到了一些错误，我认为这是关于我的数据类型但是我不能理解我应该如何编写它以防止它。

function dacmm(i0::Int64, i1::Int64, j0::Int64, j1::Int64,
        k0::Int64, k1::Int64, A::Int64, B::Int64, c::Int64, n::Int64, basecase::Int64)
## A, B, C are matrices
## We compute C = A * B
    if n > basecase
        n = n/2
        dacmm(i0, i1, j0, j1, k0, k1, A, B, c, n, basecase)
        dacmm(i0, i1, j0, j1+n, k0, k1+n, A, B, c, n, basecase)
        dacmm(i0+n, i1, j0, j1, k0+n, k1, A, B, c, n, basecase)
        dacmm(i0+n, i1, j0, j1+n, k0+n, k1+n, A, B, c, n, basecase)
        dacmm(i0, i1+n, j0+n, j1, k0, k1, A, B, C, n, basecase)
        dacmm(i0, i1+n, j0+n, j1+n, k0, k1+n, A, B, c, n, basecase)
        dacmm(i0+n, i1+n, j0+n, j1, k0+n, k1, A, B, c, n, basecase)
        dacmm(i0+n, i1+n, j0+n, j1+n, k0+n, k1+n, A, B, c, n, basecase)
    else
        for i= 1:n, j=1:n, k=1:n
            c[i+k0,k1+j] = c[i+k0,k1+j] + A[i+i0,i1+k] * B[k+j0,j1+j]
        end
    end
end

n=4;
basecase = 2;
A = [rem(rand(Int32),5) for i =1:n, j = 1:n];
B = [rem(rand(Int32),5) for i =1:n, j = 1:n];
C = zeros(Int32,n,n);

错误： ArgumentError：无效索引：1.0

Stacktrace:
 [1] to_indices at ./indices.jl:215 [inlined]
 [2] to_indices at ./indices.jl:213 [inlined]
 [3] getindex at ./abstractarray.jl:882 [inlined]
 [4] dacmm(::Int64, ::Int64, ::Int64, ::Int64, ::Int64, ::Int64, ::Array{Int64,2}, ::Array{Int64,2}, ::Array{Int32,2}, ::Float64, ::Int64) at ./In[24]:16
 [5] dacmm(::Int64, ::Int64, ::Int64, ::Int64, ::Int64, ::Int64, ::Array{Int64,2}, ::Array{Int64,2}, ::Array{Int32,2}, ::Int64, ::Int64) at ./In[24]:6
 [6] include_string(::String, ::String) at ./loading.jl:515

Answer 1

当堆栈跟踪指出时，您试图调用dacmm函数的方法，该方法在倒数第二个参数中使用Float64：

| V [4] dacmm(::Int64, ::Int64, ... ::Float64, ::Int64) at ./In[24]:16 [5] dacmm(::Int64, ::Int64, ... ::Int64, ::Int64) at ./In[24]:6

但没有这样的方法可用。你最终在那里因为n = n/2返回了一个不是整数的浮点数。

问题不会出现在original code中，因为函数的参数不受类型信息的限制。

在Julia中乘以两个矩阵

1 个答案: