You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: getLens.m
    path of file: ./repos/HoloLib-MATLAB/source
    
    the code of the file until where you have to start completion: function res_angle = getLens(f, width_Length, height_Length, width_Pixel, height_Pixel, lambda)
%菲涅尔透镜相位生成
%   P = getLens(f, Lw, Lh, Pw, Ph，lambda) 生成球面透镜的相位分布
%
%   f - 透镜的像方焦距
%   Lw  - 透镜宽度，单位：米
%   Lh - 透镜高度，单位：米
%   Pw   - 透镜宽度像素数
%   Ph  - 透镜高度像素数
%   lambda - 入射光波长，单位：米
%
%   P - 返回的相位分布矩阵

    
function res_angle = getLens(f, width_Length, height_Length, width_Pixel, height_Pixel, lambda)
%菲涅尔透镜相位生成
%   P = getLens(f, Lw, Lh, Pw, Ph，lambda) 生成球面透镜的相位分布
%
%   f - 透镜的像方焦距
%   Lw  - 透镜宽度，单位：米
%   Lh - 透镜高度，单位：米
%   Pw   - 透镜宽度像素数
%   Ph  - 透镜高度像素数
%   lambda - 入射光波长，单位：米
%
%   P - 返回的相位分布矩阵
%

k = (2*pi) / lambda;
w = linspace(-width_Length/2, width_Length/2, width_Pixel); 
h = linspace(-height_Length/2, height_Length/2, height_Pixel);
[X, Y] = meshgrid(w, h);
phi = -1*(k/2/f) * (X.*X + Y.*Y);
C = exp(1j*phi);
res_angle = mod(angle(C), 2*pi);

end