Thread Subject:

what dose this error mean -- urgency

hi every one

when i write this program it give me this eroor

why?
and what i should do to solve it

thank you


--------------------------------------
error
--------------------------------------
??? Error using ==> char
Cell elements must be character arrays.

Error in ==> ezplot at 158
      fmsg = char(f);

Error in ==> sym.ezplot at 45
   h = ezplot(char(f));

Error in ==> test7 at 33
ezplot(pin10);

------------------------------------------

code

------------------------------------------

close all
clear
clc
re=0.5;
syms k r n t
s=k*r;
m=k*re;
eps=70/9600;

%*************************************
%for n=1
%*************************************
pin1= besseli(1,s);
pin11=besselk(1,m);
pin14=pin1*pin11;
pin12=((1-eps)*besseli(1,m)*besselk(1,k)*diff(besselk(1,k)));
pin13=1/(eps*diff(besselk(1,k))*besseli(1,k)-besselk(1,k)*diff(besseli(1,k)));
pin17=pin13*pin12;
pin18=2*pin14*pin17;
pin19=cos(t);
pin10=pin18*pin19;
ezplot(pin10);

%*************************************


thank you again

no one cant answer me??????????????/
"maia " <antonietta.arista@yahoo.com> wrote in message <kdtquo$og5$1@newscl01ah.mathworks.com>...
> hi every one
>
> when i write this program it give me this eroor
>
> why?
> and what i should do to solve it
>
> thank you
>
>
> --------------------------------------
> error
> --------------------------------------
> ??? Error using ==> char
> Cell elements must be character arrays.
>
> Error in ==> ezplot at 158
> fmsg = char(f);
>
> Error in ==> sym.ezplot at 45
> h = ezplot(char(f));
>
> Error in ==> test7 at 33
> ezplot(pin10);
>
> ------------------------------------------
>
> code
>
> ------------------------------------------
>
> close all
> clear
> clc
> re=0.5;
> syms k r n t
> s=k*r;
> m=k*re;
> eps=70/9600;
>
> %*************************************
> %for n=1
> %*************************************
> pin1= besseli(1,s);
> pin11=besselk(1,m);
> pin14=pin1*pin11;
> pin12=((1-eps)*besseli(1,m)*besselk(1,k)*diff(besselk(1,k)));
> pin13=1/(eps*diff(besselk(1,k))*besseli(1,k)-besselk(1,k)*diff(besseli(1,k)));
> pin17=pin13*pin12;
> pin18=2*pin14*pin17;
> pin19=cos(t);
> pin10=pin18*pin19;
> ezplot(pin10);
>
> %*************************************
>
>
> thank you again

"maia " <antonietta.arista@yahoo.com> wrote in message <kduv99$lmv$1@newscl01ah.mathworks.com>...
> no one cant answer me??????????????/
- - - - - - - - -
  See my message in your other thread #326043

"Roger Stafford" wrote in message <kdv094$pej$1@newscl01ah.mathworks.com>...
> "maia " <antonietta.arista@yahoo.com> wrote in message <kduv99$lmv$1@newscl01ah.mathworks.com>...
> > no one cant answer me??????????????/
> - - - - - - - - -
> See my message in your other thread #326043

first thank you

you said
In diff(besselk(n,k*rs)) and diff(besseli(n,k*rs)) you apparently expect the symbolic toolbox to know the derivatives of the two modified Bessel functions, but are you sure it does? If it doesn't, you need the formula for them which you can find in Wikipedia

in the above code i use diff(besselk(1,k))
so i think it derivatives with k
and i check it separately and it dose
i think the problem lie in cos(t)
before i add cos(t) i was able to plot pin but after that it give me error

and i don't know what i should do to avoid it

"maia " <antonietta.arista@yahoo.com> wrote in message <kdv2rk$5a3$1@newscl01ah.mathworks.com>...
> "Roger Stafford" wrote in message <kdv094$pej$1@newscl01ah.mathworks.com>...
> > "maia " <antonietta.arista@yahoo.com> wrote in message <kduv99$lmv$1@newscl01ah.mathworks.com>...
> > > no one cant answer me??????????????/
> > - - - - - - - - -
> > See my message in your other thread #326043
>
> first thank you
>
> you said
> In diff(besselk(n,k*rs)) and diff(besseli(n,k*rs)) you apparently expect the symbolic toolbox to know the derivatives of the two modified Bessel functions, but are you sure it does? If it doesn't, you need the formula for them which you can find in Wikipedia
>
> in the above code i use diff(besselk(1,k))
> so i think it derivatives with k
> and i check it separately and it dose
> i think the problem lie in cos(t)
> before i add cos(t) i was able to plot pin but after that it give me error
>
> and i don't know what i should do to avoid it


in fact i want plot blow eq
http://ars.els-cdn.com/content/image/1-s2.0-S0378595510002509-si6.gif
which
?n(r, k) is like this
http://ars.els-cdn.com/content/image/1-s2.0-S0378595510002509-si7.gif
a modified Bessel function

On 26.01.13 00:01, maia wrote:

> i think the problem lie in cos(t)
> before i add cos(t) i was able to plot pin but after that it give me error

You cannot use ezplot for a formula with 3 variables. Your formula
didn't have t before you added the cos(t) term.


Christopher