## quadratic curve from matrices determinant

Hello everyone,

could someone help me please?

I would like to obtain the quadratic curve coming from the calculation of a 2×2 matrix determinant.

This is what I wrote in my code:

h = @(x,y,z) 3.*(x+5).^2 + (x + 5).*(y – 2) + (y – 2).^2;

syms x y z

w = h(x,y,z)

g = @(x,y,z) (x – 5).^2 – (x – 5).*(y – 3) + (y – 3).^2;

syms x y z

w1 = g(x,y,z)

Dhx = diff(h,x)

Dhy = diff(h,y)

Dgx = diff(h,x)

Dgy = diff(h,y)

p1 = Dhx * Dgy

expand(p1)

p2 = Dhx * Dgy

expand(p2)

exp1 = expand(p1)

exp2 = expand(p2)

Now I should do the difference between exp1 and exp2, but I can’t do it.

I am new with the symbolic toolbox, so I have difficulties to pass from symbolic expressions to numerical values.

I guess there is a faster way to calculate the determinant of my matrix and thus get the quadratic function but I don’t really know how to find it.

Thank you very much for your support!

LauraHello everyone,

could someone help me please?

I would like to obtain the quadratic curve coming from the calculation of a 2×2 matrix determinant.

This is what I wrote in my code:

h = @(x,y,z) 3.*(x+5).^2 + (x + 5).*(y – 2) + (y – 2).^2;

syms x y z

w = h(x,y,z)

g = @(x,y,z) (x – 5).^2 – (x – 5).*(y – 3) + (y – 3).^2;

syms x y z

w1 = g(x,y,z)

Dhx = diff(h,x)

Dhy = diff(h,y)

Dgx = diff(h,x)

Dgy = diff(h,y)

p1 = Dhx * Dgy

expand(p1)

p2 = Dhx * Dgy

expand(p2)

exp1 = expand(p1)

exp2 = expand(p2)

Now I should do the difference between exp1 and exp2, but I can’t do it.

I am new with the symbolic toolbox, so I have difficulties to pass from symbolic expressions to numerical values.

I guess there is a faster way to calculate the determinant of my matrix and thus get the quadratic function but I don’t really know how to find it.

Thank you very much for your support!

Laura Hello everyone,

could someone help me please?

I would like to obtain the quadratic curve coming from the calculation of a 2×2 matrix determinant.

This is what I wrote in my code:

h = @(x,y,z) 3.*(x+5).^2 + (x + 5).*(y – 2) + (y – 2).^2;

syms x y z

w = h(x,y,z)

g = @(x,y,z) (x – 5).^2 – (x – 5).*(y – 3) + (y – 3).^2;

syms x y z

w1 = g(x,y,z)

Dhx = diff(h,x)

Dhy = diff(h,y)

Dgx = diff(h,x)

Dgy = diff(h,y)

p1 = Dhx * Dgy

expand(p1)

p2 = Dhx * Dgy

expand(p2)

exp1 = expand(p1)

exp2 = expand(p2)

Now I should do the difference between exp1 and exp2, but I can’t do it.

I am new with the symbolic toolbox, so I have difficulties to pass from symbolic expressions to numerical values.

I guess there is a faster way to calculate the determinant of my matrix and thus get the quadratic function but I don’t really know how to find it.

Thank you very much for your support!

Laura symbolic, determinant, quadratic function MATLAB Answers — New Questions