Solve 2 equation with 2 unknows, solve doesn't work.

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Mehmet Emin 2018-10-9

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https://ww2.mathworks.cn/matlabcentral/answers/422978-solve-2-equation-with-2-unknows-solve-doesn-t-work

编辑： Matt J 2018-10-9

I have a function as shown below. The variables inside "pinch()" are all known values. I have two equations(eqn1 & eqn2) and two unknowns(xt & yt). It seems that I'm using solve in a wrong way because I get very very very long numbers as answer and a warning "Possibly spurious solutions. [solvelib::checkVectorSolutions]". What am I doing wrong? I appreciate any help.

Thank you.

function [sol_xt,sol_yt,sol_zt] = pinch(x1,y1,z1,az1,el1,lat1,lon1, x2,y2,z2,az2,el2,lat2,lon2);
k1 = tand(az1)
k2 = tand(az2)
A1 = k1*sind(lat1)*cosd(lon1)-sind(lon1)
B1 = k1*sind(lat1)*sind(lon1)+cosd(lon1)
C1 = k1*cosd(lat1)
A2 = k2*sind(lat2)*cosd(lon2)-sind(lon2)
B2 = k2*sind(lat2)*sind(lon2)+cosd(lon2)
C2 = k2*cosd(lat2);
syms xt yt;
R1 = sqrt( (xt-x1)^2 + (yt-y1)^2 )
R2 = sqrt( (xt-x2)^2 + (yt-y2)^2 )
eqn1 = (xt-x1)*A1 + (yt-y1)*B1 - C1*tand(el1)*R1 == 0
eqn2 = (xt-x2)*A2 + (yt-y2)*B2 - C2*tand(el2)*R2 == 0
eqns = [eqn1, eqn2];
vars = [xt yt];
[sol_xt, sol_yt] = solve(eqns, vars)
sol_zt1 = R1*tand(el1) + z1
sol_zt2 = R2*tand(el2) + z2
sol_zt = (sol_zt1+sol_zt2) / 2
end