Coverage for yasfpy/functions/t_entry.py: 83%

1import sys, os 

2 

3sys.path.append(os.getcwd()) 

4import yasfpy.log as log 

5 

6from scipy.special import spherical_jn, spherical_yn 

7 

8 

9def t_entry(tau, l, k_medium, k_sphere, radius, field_type="scattered"): 

10 """ 

11 Computes an entry in the T Matrix for a given l, k, and tau 

12 

13 **Note**: scipy.special has also derivative function. Why is it not the same? 

14 Example: 

15 Now: djx = x * spherical_jn(l-1, x) - l * jx 

16 Possible: djx = spherical_jn(l, x, derivative=True) 

17 """ 

18 m = k_sphere / k_medium 

19 x = k_medium * radius 

20 mx = k_sphere * radius 

21 

22 jx = spherical_jn(l, x) 

23 jmx = spherical_jn(l, mx) 

24 hx = spherical_jn(l, x) + 1j * spherical_yn(l, x) 

25 

26 djx = x * spherical_jn(l - 1, x) - l * jx 

27 djmx = mx * spherical_jn(l - 1, mx) - l * jmx 

28 dhx = x * (spherical_jn(l - 1, x) + 1j * spherical_yn(l - 1, x)) - l * hx 

29 

30 if (field_type, tau) == ("scattered", 1): 

31 return -(jmx * djx - jx * djmx) / (jmx * dhx - hx * djmx) # -b 

32 elif (field_type, tau) == ("scattered", 2): 

33 return -(m**2 * jmx * djx - jx * djmx) / ( 

34 m**2 * jmx * dhx - hx * djmx 

35 ) # -a 

36 elif (field_type, tau) == ("internal", 1): 

37 return (jx * dhx - hx * djx) / (jmx * dhx - hx * djmx) # c 

38 elif (field_type, tau) == ("internal", 2): 

39 return (m * jx * dhx - m * hx * djx) / (m**2 * jmx * dhx - hx * djmx) # d 

40 elif (field_type, tau) == ("ratio", 1): 

41 return (jx * dhx - hx * djx) / -(jmx * djx - jx * djmx) # c / -b 

42 elif (field_type, tau) == ("ratio", 2): 

43 return (m * jx * dhx - m * hx * djx) / -( 

44 m**2 * jmx * djx - jx * djmx 

45 ) # d / -a 

46 else: 

47 logger = log.scattering_logger("t_entry") 

48 logger.warning("Not a valid field type provided. Returning None!") 

49 return None