The Slope Field Generator app allows you to generate slope fields for first-order differential functions. This app permits the use of multi-touch gestures to navigate through the graph and zoom in/out in a given domain and range. Slopes are indicated with RGB gradients to easily distinguish between rapidly increasing tangents and decreasing. Supported functions include basic trigonometry (sin, cos, tan), and scientific constants (e, pi). Feel free to view the project on GitHub.
These is a simple screenshot of the app, showing a slope field with the differential equation of
dy / dx = (x + y) / 10.
Simple demonstration of the Android app and how it works.