It strikes me that to say that software cannot be patented because it derives from mathematical algorithms is a specious argument at best. Perhaps a couple of tongue in cheek examples may help to enlighten things:

You can use the same reductionist "logic" to say that written language is nothing more than a collection of words, or even of individual letters. Nobody owns a patent on the letter "E" or on the word "and" (to take two very simple examples) so how can authors be so presumptious as to claim copyright for their works? After all, they've not produced anything that the apocryphal infinite monkeys at infinite typewriters could produce.

What about music? In western music there are only around 60-80 main notes, and obviously it's not possible to claim a patent on middle C. All these musicians have done is just put together notes in a certain way.

Of course software can be copyrighted. If nothing else it's most certainly intellectual property, and that's exactly the kind of thing that copyright laws were brought in to protect. As to whether software ought to be copyright, well that's a whole different ball game.