Completely agree with the other poster. If you want a pair of pants and jacket to match, then buy a suit. Unless you know the exact make and model of the trousers and can find out if the same company makes a matching jacket, you'll look like you tried to match and failed. There may be slight color or pattern differences but they will be noticeable. Even if you figure out the exact make and model of the trousers AND the company that makes the trousers makes a matching suit coat, if you've worn the trousers much already, they will have a different wear pattern and you can still find yourself in trouble.
The best thing to do with these trousers is to wear them with an odd jacket, perhaps in either a cream or tan. They're definitely a summer look. At this point, I'd be thinking about what jacket and trouser combinations work with the trousers, not trying to match.