yes, I think you mean that it has four results in theory ,but maple only show the principle one@Preben Alsholm 

this is worth noticing indeed.

just applyed your solution to my equation,and it worked out well fitting the reality situation in real life@Rouben Rostamian  

this problem well solved.

Still having no idea where the aqrt(i),i.e,the (−1)^1/4  comes from,though。

But since the equation is given by the former researchers, and most importantly fitting the reality,

I will call that a magic factor before further research into it.

thanks for your patient instrution. Have a good day.

it is so considerate for you to provide me with the instruction@Rouben Rostamian  

really appreciate it.

I' m sure it would help a lot in my further using of Maple.

i am sorry there is an error@Preben Alsholm 

already corrected it.

thanks for your replying and your kind help.

thanks for your recent replying@Rouben Rostamian  

I 've just found out the weird '9' is caused by the switch of text and math at the previous working process.

2D-math issue indeed

It takes a while to find out about it. 

I' ve corrected it, yet still not able to slove the equation plot issue.

so i may still need your help.

many many thaks.

@Preben Alsholm thanks for reminding me of this

i thought the maple math in the MaplePrimes editor would work too, i was wrong.
Aready uploaded the worksheet.

Iappreciate your attention and help.

thanks for telling me this@Rouben Rostamian  

never heard of this Document mode before, but sounds more editable.Worth trying.

thank you for replying,

this is a quite normal and standard solving you provided.@Rouben Rostamian  It should work if i just started my inputting.

But since I 've used at least a thousand simbol like ϕ_c   in one worksheet,

i dont know how to substitute them at one time,

impossible to change them all,

so I choose another way

to make the  
disappear,

then input

problem solved.

another solution for problem like that.

but may not be suitable for every situation ,because the input order is crucial.

many thanks for telling me this,I do mean evaluate .And it does work.

best regards

@Rouben Rostamian  

It works,problem solved. Thank you very much.@tomleslie many many thanks

Download test.mw