filtering result in matlab

this is a set of possible solutions i get from my code.but i only need three values but i get 6 possible solutions.i know that my solution can neither be negative nor it can be complex and it should show only accepted answer after ignoring other solution

there are 6 possible solutions but only three are right. now how to use loop maybe to ignore left entries as it is negative and it should only display right entries as solution

Answer 1

[Walter Roberson]

https://www.mathworks.com/matlabcentral/answers/601690-solution-of-3d-nonlinear-equation#comment_1031275

possibleSol(:, all(possibleSol>0 & imag(possibleSol)==0, 1)) 

[ali hassan]

https://www.mathworks.com/matlabcentral/answers/602674-filtering-result-in-matlab#answer_503137https://www.mathworks.com/matlabcentral/answers/602674-filtering-result-in-matlab#answer_503137HELLO sir

HOPE EVERYONE IS FINE AND GOOD.NEED SOME HELP

basically i gave 4 3D coordinates position in matlab and i got my transmitter location in coordinates.i want to plot them in matlab in 3d coordinates.

code:

x_p = 4; y_p = 5; z_p = 2;

x_1 = 8; y_1 = 9; z_1 = 5;

x_2 = 2; y_2 = 5; z_2 = 1;

x_3 = 6; y_3 = 1; z_3 = 3;

c=3.0*10^8;

t1 = 5.692820*10^-9;

t2 = -2.924173*10^-9;

t3 = -12.010097*10^-9;

syms xs ys zs %our unknowns

eqn1 = sqrt((xs-x_p)^2+(ys-y_p)^2+(zs-z_p)^2)-sqrt((xs-x_1)^2+(ys-y_1)^2+(zs-z_2)^2)-(c*t1);

eqn2 = sqrt((xs-x_p)^2+(ys-y_p)^2+(zs-z_p)^2)-sqrt((xs-x_2)^2+(ys-y_2)^2+(zs-z_2)^2)-(c*t2);

eqn3 = sqrt((xs-x_p)^2+(ys-y_p)^2+(zs-z_p)^2)-sqrt((xs-x_3)^2+(ys-y_3)^2+(zs-z_3)^2)-(c*t3);

sol = solve([eqn1, eqn2, eqn3], [xs ys zs]);

m = 1;

for n = 1:length(sol.xs)

possibleSol(1,m) = double(sol.xs(n));

possibleSol(2,m) = double(sol.ys(n));

possibleSol(3,m) = double(sol.zs(n));

m= m+1;

end

possibleSol(:, all(possibleSol>0 & imag(possibleSol)==0, 1))

output:

now i want to plot the reciever1(x1,y1,z1),receiver2(x2,y2,z2),receiver3(x3,y3,z3),receiver4(xp,yp,zp) and the coordinates i get in answer which is possibleSol(xs,ys,zs).receiver should be black and transmitter should be blue.and i also want to use legend to name the receiver.

BEST REGARDS

Answer 2

[Ameer Hamza]

idx = any(possibleSol < 0);
possibleSol(:, idx) = []

It will remove any column with negative value in it.

[ali hassan]

if i want to remove imagiary column as well??

[Walter Roberson]

idx = any(possibleSol < 0) | any(imag(possibleSol) ~=0);
possibleSol(:, idx) = []