background preloader

Numpy/Scipy

Facebook Twitter

Polynomial vs poly1d. Numpy.polyfit. Numpy.poly1d. A one-dimensional polynomial class. A convenience class, used to encapsulate “natural” operations on polynomials so that said operations may take on their customary form in code (see Examples). Examples Construct the polynomial >>> p = np.poly1d([1, 2, 3])>>> print np.poly1d(p) 21 x + 2 x + 3 Evaluate the polynomial at Find the roots: >>> p.rarray([-1.+1.41421356j, -1.-1.41421356j])>>> p(p.r)array([ -4.44089210e-16+0.j, -4.44089210e-16+0.j]) These numbers in the previous line represent (0, 0) to machine precision Show the coefficients: Display the order (the leading zero-coefficients are removed): Show the coefficient of the k-th power in the polynomial (which is equivalent to p.c[-(i+1)]): Polynomials can be added, subtracted, multiplied, and divided (returns quotient and remainder): >>> p * ppoly1d([ 1, 4, 10, 12, 9]) >>> (p**3 + 4) / p(poly1d([ 1., 4., 10., 12., 9.]), poly1d([ 4.])) asarray(p) gives the coefficient array, so polynomials can be used in all functions that accept arrays: Attributes.

Cookbook

Notes. SciPy Tutorial. SciPy Signal processing. SciPy signal.lti. SciPy.org. Wikipedia numpy. Traits[edit] The ndarray data structure[edit] The core functionality of NumPy is its "ndarray", for n-dimensional array, data structure. These arrays are strided views on memory.[2] In contrast to Python's built-in list data structure (which, despite the name, is a dynamic array), these arrays are homogeneously typed: all elements of a single array must be of the same type. Such arrays can also be views into memory buffers allocated by C, C++.

Cython and Fortran extensions to the CPython interpreter without the need to copy data around, giving a degree of compatibility with existing numerical libraries. This functionality is exploited by the SciPy package, which wraps a number of such libraries (notably BLAS and LAPACK). Limitations[edit] NumPy's arrays must be views on contiguous memory buffers. Examples[edit] Array Creation Basic Operations Universal Functions >>> a = np.linspace(-np.pi, np.pi, 100) >>> b = np.sin(a)>>> c = np.cos(a) Linear Algebra History[edit] See also[edit] References[edit] SciPy Getting Started. This page is intended to help the beginner get a handle on SciPy and be productive with it as fast as possible. What are NumPy, SciPy, matplotlib, ...? SciPy and friends can be used for a variety of tasks: NumPy‘s array type augments the Python language with an efficient data structure useful for numerical work, e.g., manipulating matrices.

NumPy also provides basic numerical routines, such as tools for finding eigenvectors.SciPy contains additional routines needed in scientific work: for example, routines for computing integrals numerically, solving differential equations, optimization, and sparse matrices.The matplotlib module produces high quality plots. With it you can turn your data or your models into figures for presentations or articles. No need to do the numerical work in one program, save the data, and plot it with another program.Using IPython makes interactive work easy. How to work with SciPy Python is a programming language, and there are several ways to approach it. NumPy User Guide. Numpy and Scipy Documentation.