twoway function to express a quadratic form

[Jaime Mac]

Hi,

How can I get the output of this graph?
twoway function y=(x+y)^2

I understand that y should be expressed in terms of x: y=f(x), but the left hand side is y(1-2x-y)=x^2. Can you please advise on how to get around this?

Thank you in advance,

[Dirk Enzmann]

Perhaps WolframAlpha will help you, see for example.

[Jaime Mac]

Thank you for your reply Dirk.

My goal is to include additional info in the graph which Stata would easily allow to do. desmos graphing is another alternative but again I can't make edits to the graph the way Stata would allow

[George Ford]

twoway function y = (x+y)^2

[Jaime Mac]

George: I obtain the following error message:
error in expression: (x+y)^2
r(111);

[Dirk Enzmann]

Perhaps you can go on from here:

twoway (function 0.5*(-2*x + sqrt(1 - 4*x) + 1), range(-2 0.5)) ///
       (function 0.5*(-2*x - sqrt(1 - 4*x) + 1), range(-2 0.5)), ///
       title("y = (x + y)²") legend(order(1 "(1)" 2 "(2)"))

[Dirk Enzmann]

I should have increased the evaluation points considerably and there is no need to use different colors:

twoway (function 0.5*(-2*x - sqrt(1 - 4*x) + 1), range(-1.5 0.5) n(100000) lcolor(cranberry)) ///
       (function 0.5*(-2*x + sqrt(1 - 4*x) + 1), range(-1.5 0.5) n(100000) lcolor(cranberry)), ///
       title(`"y = (x + y)²"') legend(off)

[Bruce Weaver]

Dirk Enzmann, how did you make that superscript 2 in your DO file? I thought one had to use {superscript}, like this:

title("y = (x + y){superscript: 2}")

[Dirk Enzmann]

I simply used the character from my keyboard, but smcl-code probably looks slightly better, it is a matter of taste or convenience.