for example x*x+y*y = 1

like

QVector<double> X(N),Y(N);

for(int i=0;i<n;i++)

{

X* = cos( i/N*2*pi);
Y = sin( i/N*2*pi);
}*

*(the problem is that not only one value of y compate with value of x)*

How to build a graph of non-function relation?Return to overview

for example x*x+y*y = 1

like

QVector<double> X(N),Y(N);

for(int i=0;i<n;i++)

{

X* = cos( i/N*2*pi);
Y = sin( i/N*2*pi);
}*

*(the problem is that not only one value of y compate with value of x)*

Use QCPCurve, as it is written in the QCPGraph documentation :)