// Dear Nikolay Kurevin

// Below is my method of debuging

x=[1:0.1:4]
y1=-(x^2)
y2=(x-5)
y3=2./y2
 
//y=y1-y3

// plot2d(x,y)   error

// why?  I remove the semicolon and I was able to figure
// out that x matrix is row vector and y matrix is column vectors
// note y3 uses dot operation that you missed in scalar
// and vector operation

y=y1-y3'

plot2d(x,y)

// I hope I have been helpful.


// Regards,

// Dr. Celso Co, Ph.D, ECE
// Department of Electronics, Computer, and Communicatin Engineering
// Schools of Science and Engineering
// Ateneo De Manila, 
// Loyla Heights, Dliman Quezon City,
// Philippines, 1108
// Email: celso.co@gmail.com