Solving Non-Linear Equations
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I am stuck up with the following program. I want to solve for 3 variables b, n, k. Please help.
for b,n,k I am getting <1x1 sym> how to get the values? Any help would be highly apprecaited.. Thanks
clear
T = 0.89;
R = 0.11;
lamda = 0.98;
d = 1.65;
pi = 3.14;
phit = 0.60;
phir = 0.31;
syms b n k;
eq1 = 'phir=atan(((-2)*k)/(1-((n)^2)-((k)^2)))';
eq2 = 'T=((1-R)^2)+((4)*(R)*(sin(phir)^2))*(exp((-((4*(pi)*k)/(lamda)))*(d)))/((1)-(R)*(exp(((4*(pi)*k)/(lamda))*(d)))^2)+((4)*(R)*(exp(((4*(pi)*k)/(lamda))*(d)))*(sin(b+phir)^2))';
eq3 = 'phit=((2)*(pi)*(n)*(d)/(lamda))+arctan(((k)*((n)^2+(k)^2-(1)))/(((k)^2+(n)^2)*(2+n)*(n)))+arctan((((R)*exp((4)*(pi)*(k))/(lamda))*(sin(b+phir)^2))/((1)-((R)*exp((4)*(pi)*(k)))/(lamda))*(cos(b+phir)^2))';
eq4 = 'b=(((2)*(pi)*(n)*(d))/(lamda))';
sol1 = solve(eq1);
sol2 = solve(eq2);
sol3 = solve(eq3);
sol4 = solve(eq4);
0 Comments
Answers (3)
Rizwana Junaid
on 15 Oct 2012
you can solve ur system by calling ode45 function. for that you will have to save all equations in one file and call the solver function from the other main file.
Walter Roberson
on 15 Oct 2012
You need to remove all of your apostrophes. If you are using R2012a or later, change your = that are in the equations to == but if you are using an earlier version, convert your A=B forms to (B)-(A) or (A)-(B) with no = or == in the definition of the expression. For example,
eq4 = (b)-((((2)*(pi)*(n)*(d))/(lamda)));
The result of your solve() is going to be a structure array with one field for each variable name. Access the field to see the value, such as
sol4.k
2 Comments
Sachin Ganjare
on 16 Oct 2012
Undefined function or method 'arctan' for input arguments of type 'sym'.
Matlab function name is 'atan' and not 'arctan'
Hope it helps!!!
3 Comments
Sachin Ganjare
on 16 Oct 2012
Edited: Sachin Ganjare
on 16 Oct 2012
Probably you do not need quotes in your equation.
Check in your version of matlab documentation.
Hope it helps!!!
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