Quadratic Function with Complex Numbers

Question

I'm writing a function in R that needs to solve the basic quadratic equation and gives you the roots. I need to print out imaginary numbers if applicable. Below is my code. Could anyone give me advice on how I could improve my coding?

quad = function(a, b, c){
 D = b^2 - 4*a*c
 if (D < 0){
   cat("The roots are", x, "and", y,"i\n");
   z < - complex(real = x, imaginary = y)
   return();
 }

 x = (-b - D^0.5)/(2*a)
 y = (-b + D^0.5)/(2*a)
 cat("The two roots are", x, "and", y, "\n");
}

Just keep in mind I'm an incredibly new R programmer, and I am aware this is an incredibly simple code. Any advice would be greatly appreciated.

Answer 1

In the line : cat("The roots are", x, "and", y,"i\n"); it will search for x and y which are not declared. Also it will calculate the roots even if D<0 so better you use if, else block like:

    if (D < 0){
       # cat("The roots are", x, "and", y,"i\n");
       # z < - complex(real = x, imaginary = y)
        cat("imaginary roots")
         }
      else{
        x = (-b - D^0.5)/(2*a)
        y = (-b + D^0.5)/(2*a)
        cat("The two roots are", x, "and", y, "\n");
      }

Answer 2

You can use this simple code.

 quadr=function(a,b,c){
   D=b^2-4*a*c
   m=ifelse(D<0,complex(1,0,sqrt(abs(k))),sqrt(k))
   c((-b+m)/(2*a),(-b-m)/(2*a))
  }

 quadr(1,1,6)
 [1] -0.5+2.397916i -0.5-2.397916i

 quadr(1,1,-6)
 [1]  2 -3