Solving a symbolic equation in one or more variables

When the following code is executed, the output is

ans =

Empty sym: 0-by-1

although b = i = yp = [1 90]

I get the same result when I let b = [1 90] or yp instead of r2p(i), although [1 90] = 1 ∠90 degrees = i. Does anyone have suggestions regarding how I should modify the code so that r2p(i) is understood to mean [1 90] (1 ∠90 degrees)? When r2p(i) is typed in the command window, the output is correct.

 f = @(x,y) 2*x*y;
x = f(30,3)*2; 
r2p = @(x) [abs(x) rad2deg(angle(x))];                      % Rectangular -> Phasor
p2r = @(x) x(1)*exp(1i*deg2rad(x(2)));                      % Phasor -> Rectangular 
pm = @(x,y) [x(1)*y(1) x(2)+y(2)];                          % Phasor Multiply
pd = @(x,y) [x(1)/y(1) x(2)-y(2)];                          % Phasor Divide
x = 3+4i;
xp = r2p(x);
yp = [1 90];
xptimesyp = pm(xp,yp);
xrtimesyr = p2r(xptimesyp);
Check = x * p2r(yp);

syms a b c 

eqn = b==r2p(i); 

solve(eqn,b)

Answer 1

[Muthu]

I just changed the last two lines of your code

eqn = [a b] ==r2p(i)

sol = solve(eqn)

To view the variable sol, you can call sol.a and sol.b to call system variables in sol -> [a b] which contains [1 90] respectively

Hope this helps.

-Muthu.

[Aleem Andrew]

Thank you for your answer

Answer 2

[Tommy]

Your equation is

>> eqn
 
eqn =
 
[ b == 1, b == 90]

which has no solution.

You could specify that b should be a 1x2 vector:

r2p = @(x) [abs(x) rad2deg(angle(x))];                      % Rectangular -> Phasor
syms b [1 2]
eqn = b==r2p(1i);

>> eqn
 
eqn =
 
[ b1 == 1, b2 == 90]

which gives

S = solve(eqn,b);

>> disp([S.b1 S.b2])
[ 1, 90]

[Aleem Andrew]

Thank you for your answer