Getting numeric and symbolic coefficients of equation of a straight line in 2d or 3d

Consider the general equation of a straight le in 3d a*x + b*y + c*z + d=0. I would like to get a vector giving [a,b,c,d] including those that are zero or infinity. a,b,c,d can be both numeric and symbolic

[Ameer Hamza]

a*x + b*y + c*z + d = 0

is an equation of plane (not line) in 3D. How do you want to find the values of [a,b,c,d]? Do you want to estimate it using curve-fitting?

[Saikat Banerjee]

Lets say as an example a equation is given as 7*x - 8*y + d. So my return value or answer is [7,-8,0,c]. I simply want the symbolic/numeric co-efficients of x, y, z, 1. including 0 coefficients

Answer 1

[Ameer Hamza]

Try this

syms x y z

f = -9*x + 7*z + 9;
cd = subs(f, [x y z], [0 0 0]);
cx = subs(f, [x y z], [1 0 0])-cd;
cy = subs(f, [x y z], [0 1 0])-cd;
cz = subs(f, [x y z], [0 0 1])-cd;
cd = subs(f, [x y z], [0 0 0]);
c = [cx cy cz cd];

[Saikat Banerjee]

function[c]=Get_coefficient_of_straight(f)
 syms x y z d
 cx = subs(f, [x y z d], [1 0 0 0]);
 cy = subs(f, [x y z d], [0 1 0 0]);
 cz = subs(f, [x y z d], [0 0 1 0]);
 cd = subs(f, [x y z], [0 0 0]);
 c = [cx cy cz cd];
 end

I made this function and experimenting with different f. Its not working. Try -9*x+7*z+9

[Ameer Hamza]

Check the updated answer!

[Saikat Banerjee]

where is your updated answer ?

[Ameer Hamza]

The code in my answer, it was changed. I changed it again now.

[Saikat Banerjee]

Thanks buddy

[Ameer Hamza]

I am glad to be of help!