Solving Ax=B where B is symbolic and x unknown?

How do I solve Ax=B when B is symbolic and x unknown?

For example, in the trivial case:

1*x+0*y=a

0*x+1*y=b

I'd like MATLAB to output x=a and y=b. (Obviously I have more complex matrices...)

I'm new to MATLAB and skimmed through the symbolic toolbox but couldn't really find what I need (or maybe found and didn't understand).

Help, please? Thanks.

p.s. How do I indicate a 'new line' in this post box? (Instead of pressing 'enter' twice)

Answer 1

[Andrei Bobrov]

eg:

A  = rand(8);
b = sym('b',[8,1]);
x = vpa(A\b,5);

ADD on Walter's comment:

for jj = 1:8
    b(jj) = sym(sprintf('b%-d',jj));
end

[Walter Roberson]

Note: the syntax sym('b',[8,1]) is relatively new (R2011a I think it was.)

[queryous]

I typed in:

A=[3 0; 0 2];

b=[sym('p'); sym('q')]

b/A

and got:

[p/3, 0]

[q/3, 0]

Instead of something meaning x=p/3 and y=q/2.

Using vpa is not helpful, gives decimal notation instead of fractions.

[queryous]

Never mind, A\b works - thanks!