numpy.sin — NumPy v1.11 Manual (original) (raw)

numpy.sin(_x_[, _out_]) = <ufunc 'sin'>¶

Trigonometric sine, element-wise.

Parameters:	x : array_like Angle, in radians ( $2 \pi$ rad equals 360 degrees).
Returns:	y : array_like The sine of each element of x.

Notes

The sine is one of the fundamental functions of trigonometry (the mathematical study of triangles). Consider a circle of radius 1 centered on the origin. A ray comes in from the $+x$ axis, makes an angle at the origin (measured counter-clockwise from that axis), and departs from the origin. The $y$ coordinate of the outgoing ray’s intersection with the unit circle is the sine of that angle. It ranges from -1 for $x=3\pi / 2$ to +1 for $\pi / 2.$ The function has zeroes where the angle is a multiple of $\pi$ . Sines of angles between $\pi$ and $2\pi$ are negative. The numerous properties of the sine and related functions are included in any standard trigonometry text.

Examples

Print sine of one angle:

Print sines of an array of angles given in degrees:

np.sin(np.array((0., 30., 45., 60., 90.)) * np.pi / 180. ) array([ 0. , 0.5 , 0.70710678, 0.8660254 , 1. ])

Plot the sine function:

import matplotlib.pylab as plt x = np.linspace(-np.pi, np.pi, 201) plt.plot(x, np.sin(x)) plt.xlabel('Angle [rad]') plt.ylabel('sin(x)') plt.axis('tight') plt.show()

(Source code, png, pdf)

../../_images/numpy-sin-1.png