Math Surface vs DuoNiu Write

3D surfaces, 2D curves, the complex plane, probability — all in one app. Type a formula and watch it come alive. Perfect for study, exploration, or just enjoying the beauty of math. Description: MathSurface turns equations into shapes you can hold, spin, and slice. It's a math playground for iPhone and iPad — designed for students, curious minds, and anyone who learns better by seeing. ■ Features • 3D surface plots: visualize z = f(x, y) with smooth rotation and pinch-to-zoom • 2D function plots: explicit y = f(x) or implicit 0 = F(x, y) curves • Complex plane: loci such as |z − α| = r, arithmetic operations, powers, and n-th roots of unity • Probability distributions: binomial and normal, controlled by live sliders • Surface of revolution: spin any 2D curve around the x- or y-axis (rendered with SceneKit) • Cross sections: slice any 3D surface with a plane and see the resulting curve • Compare mode: overlay two functions in the same plot • Preset gallery: paraboloid, monkey saddle, Mexican hat, lemniscate, and many more • Favorites: save your own custom expressions for instant recall ■ Who it's for • High school and university students studying calculus, analysis, or probability • Teachers looking for live visual aids • Anyone curious about how a formula actually looks • People who just enjoy beautiful math A custom Liquid Glass–style formula keyboard makes entering sin, cos, √, π, and friends quick and natural. The dark neon UI keeps the math front and center.

DuoNiu Write is an iOS app focused on Chinese character writing and stroke-order practice. One character per page—trace along the strokes and get instant scoring and spoken encouragement when you lift your finger. Great for students’ daily practice and for parents learning characters with their children. [Core Practice] • Enter any characters, or start from a school-curriculum poem • Automatic stroke-order demo, tianzi-grid tracing, instant scoring after each stroke • Multiple fonts including regular script, running script, and clerical script; adjustable ink color • Scores saved each time so you can track progress • Add family members’ names for quick practice of common characters [School Poetry] • Browse primary-school curriculum poems by grade • Practice writing, dictation, and recitation modes • Dictation gives line-by-line hints; view the full handwritten work when done • Recitation highlights lines in sync for easier follow-along • Save handwritten works to Photos [Peace of Mind] • No account required; no personally identifiable information collected • Practice history, scores, and settings stay on your device • Missing stroke data is downloaded only with your consent, then cached locally DuoNiu Write brings stroke order, scoring, classical poetry, and recitation together to make practice more fun and structured. Contact us via About in the app with suggestions or feedback.