Writing an expression
x is the independent variable; a, b and c are editable coefficients. Examples: 2x+1, a*x^2+b*x+c, sin(x), x^2+y^2=25, y>x, (2,3), f(x)=x^2, (cos(t),sin(t)). ^ means exponentiation. The constants pi and e are supported. Use a decimal point; commas separate function arguments.
Trigonometric functions initially use radians; select degrees in graph settings. sin(pi/2)=1; log(x) is base 10 and ln(x) is the natural logarithm.
How is the graph plotted?
Explicit functions are sampled over the visible range. Implicit equations are traced by evaluating a two-variable expression on a grid; regions that satisfy an inequality are shaded. Parametric curves are sampled over a finite t interval. Use up to 16 expressions on the same plane. Changing a quadratic’s a coefficient changes its direction and width; b and c also affect its position.
Domain and plotting limits
1/x is undefined at x=0; ln(x) has no real value when x≤0. Undefined or non-finite values are omitted. Curves are numerical samples: very narrow features, high frequencies and some discontinuities may be missed. A plot is not proof of a root, intersection or exact result. Functions, implicit equations, inequalities, points and parametric curves over a finite t interval are supported. Implicit curves are approximated on a grid; very small components and tangent points may be missed. Point tables support up to 64 coordinate pairs. “Add linear fit” calculates the least-squares line and R² for the current points; add a new fit after editing the data. Parametric curves are sampled from t=0 to 2π. Symbolic algebra, nonlinear regression and 3D surfaces are not included.
Inputs and downloads
Expressions and graphs are processed on your device. Saving is optional and uses browser storage; a shared link contains the expressions in its fragment. A PNG is created only when you select download. Calculation inputs are not sent to a server.
Mathematics reference: OpenStax — Calculus, Trigonometric Functions