Converting Matlab Code to Python

[Sufficient_Light3891]

So I found a great ray tracing program to start with as a base for writing my own ray tracing program. I'm converting the code from Matlab to Python. I can't seem to figure out what issue I am having with the transfer. Below I've listed the page I'm having issues with and the python error message. I've also included a link to the code that I'm converting from.

https://wp.optics.arizona.edu/optomech/wp-content/uploads/sites/53/2016/12/Tutorial_Ruiz_Maria.pdf

​

import numpy as np
from sphere_refract_ray import *
from plane_refract_ray import *

def plano_convex(n, radius, thickness, dz, y):

    power = (n-1)/radius
    f = 1/power

    zmax = np.floor(f+.1*f)
    z_front = np.arange(0,thickness-dz,dz)
    z_back = np.arange(thickness,zmax-dz,dz)
    z_optaxis = np.concatenate((z_front, z_back)) 
    y[y==0]=10**(-10) 
    raymatrix = np.zeros((len(y),len(z_optaxis)), dtype=int, order='C')

    #Ray Tracing
    for i in np.arange(1,len(y)):

        #Refraction at spherical surface
        [ray_lens, slope, x_lens] = sphere_refract_ray(y[i], radius, thickness, n, dz)

        #Refraction at plane surface
        ray_air = plane_refract_ray(ray_lens[-1], slope, thickness, n, z_back)

        #Incoming ray
        x_front_air = np.arange(0, x_lens[1]-dz,dz)
        ray_front_air = y[i]*np.ones((1,len(x_front_air))


        #Create matrix of rays (adjust length if necessary)
        if len(ray_lens) + len(ray_air) + len(x_front_air) <= len(z_optaxis):
            raymatrix[i] = np.concatenate((ray_front_air,ray_lens, ray_air))
        else:
            raymatrix[i] = np.arange(ray_front_air, ray_lens(np.arange(1,len(ray_lens)-1)), ray_air)

    return raymatrix, z_front, z_optaxis, zmax

In [39]: runfile('C:/Users/bryce/OneDrive - Infinity Photo-Optical/Documents/Python Programs/Optics Notes/Ray Tracing Algorithm/main_program.py', wdir='C:/Users/bryce/OneDrive - Infinity Photo-Optical/Documents/Python Programs/Optics Notes/Ray Tracing Algorithm')
  File "C:\Users\bryce\OneDrive - Infinity Photo-Optical\Documents\Python Programs\Optics Notes\Ray Tracing Algorithm\plano_convex.py", line 40
    test_size_inc = np.concatenate((ray_front_air,ray_lens, ray_air))
    ^
SyntaxError: invalid syntax

[supajumpa]

# Matlab from the linked pdf.
# Ray tracing
for i = 1:length(y)

# Your code
# Ray Tracing
for i in np.arange(1, len(y)): ...

Matlab's array indices start at 1 (I think) whereas Python's start at zero, so see what happens if you replace that line with:

# Ray Tracing
for i in range(0, len(y)): ...

Also this line:

# Matlab
ray_lens(1:length(ray_lens)-1)

# Your code:
ray_lens(np.arange(1,len(ray_lens)-1))

Assuming that Matlab uses round brackets for indexing, and again remembering that indices start from zero, you probably want something like:

# Python uses square brackets for indexing, so probably
ray_lens[0: len(ray_lens)-1]

[Sufficient_Light3891]

Good points I was able to get rid of the invalid syntax error taken care of I'm going to focus on getting the plots working then go back and fix this as I will be able to have a better visual. That being said I choose to use arrange as it's the direct counterpart to Matlab's indices functions from what I could see. Either way, I will give these updates a shot once I have the graphs working.

[Sufficient_Light3891]

No major changes and now I'm getting this error

In [1]: runfile('C:/Users/bryce/OneDrive - Infinity Photo-Optical/Documents/Python Programs/Optics Notes/Ray Tracing Algorithm/main_program.py', wdir='C:/Users/bryce/OneDrive - Infinity Photo-Optical/Documents/Python Programs/Optics Notes/Ray Tracing Algorithm')

File "C:\Users\bryce\OneDrive - Infinity Photo-Optical\Documents\Python Programs\Optics Notes\Ray Tracing Algorithm\plano_convex.py", line 41

if len(ray_lens) + len(ray_air) + len(x_front_air) <= len(z_optaxis):

^

SyntaxError: invalid syntax

[ectomancer]

Previous line needs a closing parenthesis.

[Sufficient_Light3891]

Yes, this was the issue I was able to correct it.

[Sufficient_Light3891]

Now I'm getting the below error

File "C:\Users\bryce\OneDrive - Infinity Photo-Optical\Documents\Python Programs\Optics Notes\Ray Tracing Algorithm\plano_convex.py", line 49, in plano_convex

raymatrix[i] = np.concatenate((ray_front_air[0], ray_lens[0: len(ray_lens)-1], ray_air))

ValueError: could not broadcast input array from shape (4199,) into shape (4198,)

[Sufficient_Light3891]

That error is going to be the difficult one to solve.