Why could this happen?

General Usage
1

I used Expr to express a very very complicated math expression. I used println(io,expr) to put it into a file.
The size of the file is 480KB.
When I opened the file (using vscode,so I’m sure the problem is not here), I found it ended in -, with unclosed (, by the way there’s no new line.

enviroment:

  • windows10
  • julia1.6.1
2

Without knowing what that expression is, it’s kind of impossible to find out.

1 Like
3

I’m sorry but it’s too long.

4

Could you share a working example of the code that generates it?

5

Can you share how you arrived at that expression? Or maybe upload the code to some third party (e.g. gist.github.com) to not clutter discourse?

6 
# does derivation
function der(a::Symbol)
    if a==:x
	    return 1
    else
	    return 0
    end
end
function der(a::Int)
    return 0
end
function der(a::Expr)
    f=a.args[1]
    if f==:+
	    return Expr(:call,:+,der(a.args[2]),der(a.args[3]))
    elseif f==:-
	    return Expr(:call,:-,der(a.args[2]),der(a.args[3]))
    elseif f==:*
	    return Expr(:call,:+,Expr(:call,:*,a.args[2],der(a.args[3])),Expr(:call,:*,der(a.args[2]),a.args[3]))
    elseif f==:/
	    return :($(der(a.args[2]))*$(a.args[3])-$(a.args[2])*$(der(a.args[3]))/$(a.args[3])^2)
    elseif f==:ln
	    return :($(der(a.args[2]))/$(a.args[2]))
    elseif f==:^
	    return :($(der(a.args[3]))*($(a.args[3])*$(a.args[2])^($(a.args[3])-1)+ln($(a.args[2]))*$(a.args[2])^$(a.args[3])))
    else # can ignore
	    return Expr(:call,0)
    end
end
f=:(x^x^x^x^x^x)
io=open("D:/1.txt","w")
println(io,der(der(der(der(f)))))
7

I ran the code again and the file stopped at the same place.

8

Try to add close(io) at the end.

Note that it is recommended to let Julia close the file automatically using the do block syntax:

open("D:/1.txt","w") do io
    println(io,der(der(der(der(f)))))
end

instead of

io = open(...)
println(io, ...)
close(io)
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