Can someone explain why I keep getting this error? and please tell me how I can correct it, thank you. This is MATLAB.

| | | function dAdW = PBRrun (W, A) dAdW = zeros (2,1); global k eps Fao alpha Cao thetab sharing variables with main script eps = (1-2-1)/3; Ca0 = .2; thetab= 2; Fa0 = 2; k = 6; alpha = 0.02; dAdW (1) = ((k) * (Ca0* ((1-A(1))/(1+eps*A(1))) *A(2)) * (Ca0* (((thetab-2*A(1))/(1+eps *A(1)))) *A(2)) ^2). dAdW (2) = -alpha * ((1+eps *A(1))/(2*A(2))); $A (2) is y(P/PO) | ommand Window >> PBRrun (W, A) Unrecognized function or variable 'W