Features ++++++++ What grafity does ----------------- * Simple 2D line and scatter plots. * Operations on curves (move, scale, derivative/integral, interpolate/extrapolate, smoothing, denoise using wavelets, Fourier transform, add/subtract/multiply with another dataset). Operations can be individually enabled/disabled, modified and removed. * Nonlinear curve fitting: * Fit with a sum of terms which can be independently added and enabled/disabled. * Easily fit multiple curves sharing fit parameters. * ODR (orthogonal distance regression) for data with both X and Y uncertainties. * Parameter dependencies, to identify redundant parameters. * Easy graphical setting of initial values by dragging the fit curves. * Additional analysis tools such as: find peaks, analyze peak, analyze step (e.g. glass transition), find onset point. * Do calculations and define fit functions using `Python `_. All the functions in `NumPy `_ are available. * Unlimited **undo/redo** of all operations. * Cross-platform: runs on **Windows, Mac OS X and Linux**. Dielectric Spectroscopy ----------------------- Grafity has some features that are useful for fitting dielectric spectroscopy data: * Built-in fit functions for DRS such as: Havriliak-Negami (various forms), KWW in freq. domain, Rouse model, VTF, Arrhenius. * Easily fit real and imaginary part of dielectric permittivity simultaneously. * Fast and accurate KWW function in the frequency domain (based on code from `LEVMW `_). * On-the-fly transform from time to frequency domain (based on F.I. Mopsik, *J. Res. NIST*, **104**, 189 (1999)). This allows directly fitting frequency domain data with functions defined in the time domain (e.g. "Williams ansatz") without needing to transform your data.