alphaVal=fminimum(phiAlpha1)

function alphaVal=fminimum(phiAlpha1)
%solve the optimization problem of one-variable function phiAlpha1
%return the minimum point
syms alpha1
diffRoots=solve(diff(phiAlpha1,alpha1),'alpha1');%calculate stop points
diffRoots=eval(diffRoots);
diffRoots=removeComplexVals(diffRoots);%remove complex stop points
[C I]=min(subs(phiAlpha1,alpha1,diffRoots));
alphaVal=diffRoots(I);%return the minimum point