Let's say there is a software company. This company is developing a Digital Signal Processing software library. The library doesn't constitute an application itself but it is meant to be sold to be used in a bigger software. For simplicity, we assume that the library has been written from scratch, without the use of any other external libraries.
Anyway the library implements some algorithms that have been patented, from other entities, for specific applications.
Does the company has to care about patents at all? Does the company has to warn the client about the specific patented applications? Since the library has been written from scratch, may the client pretend to use the library to implement a patented application?