It is unfortunate that qr does not produce a solution for the linear case (when A is 0). However,
qr=. _2 * C % (B + (+ , -) @:%:@:(*:@:B - 4 * A * C)) does, qr 0 _8 6 __ 0.75 qr 2 _8 6 3 1 On Mon, Nov 9, 2015 at 12:34 PM, Jose Mario Quintana < [email protected]> wrote: > Tacitly... > > (A=. 0&{) (B=. 1&{) (C=. 2&{) > 0&{ 1&{ 2&{ > > qr=. (-@:B + (+ , -) @:%:@:(*:@:B - 4 * A * C)) % 2 * A > quad=. qr`('Not quadratic'"_)@.(0 -: A) f. > > quad 2 _8 6 > 3 1 > quad 0 _8 6 > Not quadratic > > > On Mon, Nov 9, 2015 at 2:26 AM, Don Kelly <[email protected]> wrote: > >> If you assume the form is ax^2 +bx +c =0 then all you have to do is >> check for a=0 >> 0=0{ a b c is true so not quadratic and flag it if true >> >> Don Kelly >> >> >> On 11/6/2015 3:18 PM, Kip Murray wrote: >> >>> Most of us have heard of the quadratic formula >>> >>> x = ( -b +or- %: (b^2 - 4ac) )/2a (roughly standard math notation) >>> >>> for solving ax^2 + bx + c = 0 for x . >>> >>> Your mission, should you decide to accept it, is to write a verb quad >>> that takes >>> vector a,b,c as argument, says “Not quadratic” if a is 0 , and >>> otherwise >>> uses the quadratic formula to find the values of x, reporting them in a >>> vector. >>> >>> quad 2 _8 6 >>> 3 1 >>> >>> quad 0 _8 6 >>> Not quadratic >>> >>> --Kip Murray >>> >>> >>> >>> >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm >> > > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
