1from math import pi, sin, cos, hypot, sqrt
2
3# Math functions
4
5def degToRad(deg):
6    return (deg/180.0)*pi
7
8def radToDeg(rad):
9    return (rad/pi)*180.0
10
11def polarToRect(polar):
12    r = polar[0]
13    theta = polar[1]
14    return (r*cos(theta), r*sin(theta))
15
16def bessel(z, t=0.00001):
17    j = 1
18    jn = 1
19    zz4 = z*z/4
20    for k in range(1, 100):
21        jn *= -1 * zz4 / (k*k)
22        j += jn
23
24        if jn < 0:
25            if jn > t:
26                break
27        else:
28            if jn < t:
29                break
30    return j
31