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Thread Subject:
Matrix 8x8

Subject: Matrix 8x8

From: george veropoulos

Date: 26 Jun, 2010 20:31:06

Message: 1 of 3

Hi dear friends
 I have defined a symbolic matrix A (8,8) .
 The matrix have many parameters that dependent form the uknow variable E.
 I would like to solve the equation det(A)=0 and find the various values for E.
 
The problem is that the matrix that Matlab computes becomes very difficult to handle. In fact the program runing for many hours without any results.
thank you
What should I do?
 Many thanks

**************** The full code *********************************

digits(2);

syms E;

D=0;
L=1;
L1=1;
V0=4;
m1_star=1;
m2_star=2;
m3_star=3;
m4_star=4;
m5_star=5;
h_bar=1;
k_1=(2*m1_star/h_bar^2)^0.5*(E-V0).^0.5;
k_2=(2*m2_star/h_bar^2)^0.5*E.^0.5;
k_3=(2*m3_star/h_bar^2)^0.5*(E-V0).^0.5;
k_4=(2*m4_star/h_bar^2)^0.5*E.^0.5;
k_5=(2*m5_star/h_bar^2)^0.5*(E-V0)^0.5;
A11=-exp(i*k_2*(D+L));
A12=0;
A13=0;
A14=0;
A15=exp(-i*k_1*(D+L));
A16=exp(i*k_2*(D+L));
A17=0;
A18=0;
A21=(i*k_2/m2_star)*exp(i*k_2*(D+L));
A22=0;
A23=0;
A24=0;
A25=(i*k_1/m1_star)*exp(-i*k_1*(D+L));
A26=(-i*k_2/m2_star)*exp(-i*k_2*(D+L));
A27=0;
A28=0;
A31=exp(i*D*k_2);
A32=-exp(-i*k_4*D);
A33=0;
A34=0;
A35=0;
A36=exp(-i*k_2*D);
A37=-exp(-i*k_3*D);
A38=0;
A41=(i*k_2/m2_star)*exp(i*k_2*D);
A42=(i*k_3/m3_star)*exp(i*k_3*D);
A43=0;
A44=0;
A45=0;
A46=-(i*k_2/m2_star)*exp(-i*k_2*D);
A47=(i*k_3/m3_star)*exp(-i*k_3*D);
A48=0;
A51=0;
A52=exp(-i*k_3*D);
A53=-exp(-i*k_4*D);
A54=0;
A55=0;
A56=0;
A57=exp(i*k_3*D);
A58=-exp(i*k_4*D);
A61=0;
A62=(i*k_3/m3_star)*exp(-i*k_3*D);
A63=-(i*k_4/m4_star)*exp(-i*k_4*D);
A64=0;
A65=0;
A66=0;
A67=-(i*k_3/m3_star)*exp(i*k_3*D);
A68=-(i*k_4/m4_star)*exp(i*k_4*D);
A71=0;
A72=0;
A73=exp(-i*k_4*(D+L1));
A74=exp(-i*k_5*(D+L));
A75=0;
A76=0;
A77=0;
A78=exp(i*k_4*(D+L1));
A81=0;
A82=0;
A83=(i*k_4/m4_star)*exp(-i*k_4*(D+L1));
A84=-(i*k_5/m5_star)*exp(-i*k_5*(D+L1));
A85=0;
A86=0;
A87=0;
A88=-(i*k_4/m4_star)*exp(D+L1)
A=vpa([A11 A12 A13 A14 A15 A16 A17 A18 ;A21 A22 A23 A24 A25 A26 A27 A28 ;A31 A32 A33 A34 A35 A36 A37 A38 ;A41 A42 A43 A44 A45 A46 A47 A48;..../
    A51 A52 A53 A54 A55 A56 A57 A58 ;A61 A62 A63 A64 A65 A66 A67 A68; A71 A72 A73 A74 A75 A76 A77 A78; A81 A82 A83 A84 A85 A86 A87 A88 ])

solve(det(A), 'E')

Subject: Matrix 8x8

From: Matt Fig

Date: 26 Jun, 2010 20:55:05

Message: 2 of 3

How many times are you going to post the same question today?

Subject: Matrix 8x8

From: george veropoulos

Date: 26 Jun, 2010 21:03:05

Message: 3 of 3

"Matt Fig" <spamanon@yahoo.com> wrote in message <i05pf9$cj8$1@fred.mathworks.com>...
> How many times are you going to post the same question today?

sorry mat ... but im trying to be more specific
it is the fisrt time that i posted a question...

sorry again

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