Julia 内置函数求和数组？

Question

在 Julia 中是否没有内置函数来对数字数组求和？

x = rand(10)
sum(x) # or sum(x, 1)

ERROR: MethodError: objects of type Float64 are not callable

我的意思是我可以写一个 for 循环来总结如下，

sum = 0.0    
for i in 1:length(x)
    sum += x[i]
end

但如果 julia 没有把这个内置在某个地方，我会感到惊讶吗？

Answer 1

如 @Michael K. Borregaard提到，您重新分配了变量 sum (默认从 Base 导出)，值为 Float64在某一点。当您重述 session 时，sum又是 Base.sum默认，即:

julia> x = rand(10)         
10-element Array{Float64,1}:
 0.661477                   
 0.275701                   
 0.799444                   
 0.997623                   
 0.731693                   
 0.557694                   
 0.833434                   
 0.90498                    
 0.589537                   
 0.382349        

julia> sum                                                    
sum (generic function with 16 methods)                        

julia> sum(x)               
6.733930084133119 

julia> @which sum(x)                                          
sum(a) in Base at reduce.jl:359     

注意警告:

julia> original_sum = sum
sum (generic function with 16 methods)

julia> sum = x[1]                                             
WARNING: imported binding for sum overwritten in module Main  
0.6614772171381087                                                

julia> sum(x)                                                 
ERROR: MethodError: objects of type Float64 are not callable  

julia> sum = original_sum
sum (generic function with 16 methods)

julia> sum(x)               
6.733930084133119