Feature-Based Panoramic Image Stitching Preallocating Arrays

In reference to https://www.mathworks.com/help/vision/examples/feature-based-panoramic-image-stitching.html?requestedDomain=www.mathworks.com, I tried the code provided. But Matlab is giving me the following error:

It's saying that the size of xlim and ylim change with each iteration, and asked me to consider preallocating my arrays. I'm a beginner at Matlab, and have no idea what this means. Would appreciate any help!