朱莉娅内置了数组总和的功能？

Question

在朱莉娅,没有内置函数来汇总一组数字？

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

但是如果朱莉娅没有把它建在某个地方,我只会感到惊讶吗？

Answer 1

正如@Michael K. Borregaard所提到的那样,你在某个时刻用a的值重新设置了变量sum(默认情况下从中导出Base)Float64.当您重新开始会话时,sum再次是Base.sum默认值,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