MATLAB: How to use function equationTomatrix in matlab2012 b.? it shows error for following code

Extended Symbolic Math ToolboxMATLABsymbolicSymbolic Math Toolbox

I have following symbolic variables

% T1 T2 T3

T = sym('T',[1 3])

Eqn = 3*T(1) – 5*T(2) + 2*T(3)==5

[A b]= EquationTomatrix(Eqn,T)

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The routine name is equationsToMatrix with a lower-case 'e' and with plural 'equations'

Related Solutions

MATLAB: How to get numerical value from symbolic variables equation

iwant = subs(Eqn,T(3)) ;
iwant = double(iwant) ;

You have to substitute T(3) in the equation.

MATLAB: Am I unable to solve multivariate ODE boundary value problems using DSOLVE with MuPAD in Symbolic Math Toolbox 5.1 (R2008b)

This enhancement has been incorporated in Release 2009b (R2009b). For previous product releases, read below for any possible workarounds:

The ability to solve a system of ODEs with non-constant boundary conditions is not available in Symbolic Math Toolbox 5.1 (R2008b). The documentation for DSOLVE states that the initial conditions may be specified by equations like y(a)=b or Dy(a)=b where a and b are constants. Maple may be able to accept a more general type of boundary conditions, but since MuPAD is not explicitly stated to handle such specifications, it cannot be guaranteed to work with such specifications.

You may be able to work around this by first solving the system without the flux conditions to receive a solution involving constants. You can then use the SOLVE function with these conditions to solve the algebraic system of equations to determine the values of the constants and then substitute these back in the original solution.

syms t
soln = dsolve('D2T1/5 - 2*DT1 = 0', 'D2T2/5 - 2*DT2 + 5000 = 0',...
'D2T3/5 - 2*DT3 = 0', 'T1(0) = 20', 'T3(1) = 100');
eqs{1} = subs(soln.T1, t, .2) - subs(soln.T2, t, .2); % = 0
eqs{2} = subs(soln.T2, t, .4) - subs(soln.T3, t, .4);
eqs{3} = subs(diff(soln.T1,t), t, .2) - subs(diff(soln.T2,t), t, .2);
eqs{4} = subs(diff(soln.T2,t), t, .4) - subs(diff(soln.T3,t), t, .4);
constvals = solve(eqs{:});
constnames = fieldnames(constvals);
Soln.T1 = subs(soln.T1, constnames.', struct2cell(constvals).');
Soln.T2 = subs(soln.T2, constnames.', struct2cell(constvals).');
Soln.T3 = subs(soln.T3, constnames.', struct2cell(constvals).');

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Related Solutions

MATLAB: How to get numerical value from symbolic variables equation

MATLAB: Am I unable to solve multivariate ODE boundary value problems using DSOLVE with MuPAD in Symbolic Math Toolbox 5.1 (R2008b)

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