Sometimes people say that you should avoid reinventing the wheel, as if reinventing the wheel was a bad thing! I contend that the opposite is true: reinventing the wheel is most often a good thing. In fact, I think that science and technology advance essentially by reinventing the wheel: that is, revisiting again and again old ideas, looking at them in a new context, and slightly adapting them to fit better. Or even not adapting them at all: reproducing experiments exactly as they were done before is one of the cornerstones of the scientific method.
People with extreme pride do not like to reproduce the experiences of others. That is alright. The world needs Newtons and Einsteins. However, the next time you refuse to write your own function to multiply two matrices, bear in mind that Newton himself polished his own lenses. Polishing a single piece of glass by hand takes several days of work. But Newton did it himself, even if this was a well-known technique at the time, and there were excellent lens makers in England. If Newton could set aside some weeks of his genius time to polish the lenses for his experiments, then most of us can spend an afternoon writing a function to read an image from a JPEG file. You may learn something new in the process. After all, a famous insight of Newton on the nature of light was inspired by the observation that glass is polished by scratching it by successively finer sandpaper. Would this insight have existed if he had not “lost” many hours polishing glass?
Let us go forth and reinvent the wheel many, many times!