@Carl Love 

tks for your help , but this function is too complex for me since i have a lot of simlimar equations set need be solved in the furture.   just want use fsolve() or other similar other numerical functions two solve an 4 variables equations set at one time.  

anyways , tks again, hoping you can give me some good solutions. 

Dear:

  tks for your help, the problem has been solved. but another problem occurs:

   when i try change numeric formatting from fixed to scienific by context menu command ,the 2D output has no response, it still keep fixed type. how can i solve this problem?

 tks very much !

 Best regards

Andy

Dear:

  tks for your help, the problem has been solved. but another problem occurs:

   when i try change numeric formatting from fixed to scienific by context menu command ,the 2D output has no response, it still keep fixed type. how can i solve this problem?

 tks very much !

 Best regards

Andy

Dear Robert:

   can you tried my example in your maple software? i'm sure it really happend in my maple software

  my maple version: maple 13.

 example: View 8241_sample.mw on MapleNet or Download 8241_sample.mw
View file details

Dear Robert:

   can you tried my example in your maple software? i'm sure it really happend in my maple software

  my maple version: maple 13.

 example: View 8241_sample.mw on MapleNet or Download 8241_sample.mw
View file details

the problem has been solved!

the problem has been solved!

i wat set Ipk:=10,where pk is subscript, but error message shows:"  Error, illegal use of an object as a name"

tks very much!

Dear All:

    If i want the manitude and phase curve display by different color like blue and red, how could i do that !

tks very much !

Andy

tks very much everyone for concerning my problem!

 I want to archevied as following:

could this be relized in maple?

  i had used the covert fundtion, but the resutlt is sinh and cosh function, what i want is  sin or cos function. So what should i do?

  the ode system is dsolve([ip(t)+Cp*(diff(vp(t), t)) = 0, Lm*(diff(im(t), t)) = vs(t), Lp*(diff(ip(t), t))+vs(t) = vp(t), ip(t) = im(t)+Cs*(diff(vs(t), t)), im(0) = Ip1, ip(0) = Ip1, vs(0) = 0, vp(0) = 0], {im(t), ip(t), vp(t), vs(t)}) 

  are there any softwares or methods can do this ?  

I'm looking forward to your help! thanks!