The eight-person jury hearing Apple's patent infringement case against Samsung was thrown into the deep end Monday and subjected to some heady talk of subroutines and class libraries.

It was a big contrast to last week, when the court got a behind-the-scenes look at the birth of the iPhone and were told of a Steve Jobs email in which the former Apple boss called for a "holy war" against Google.

But the technical discussion Monday was inevitable in a patent case and could do much to determine the outcome of the trial. It's not enough to prove a defendant built similar features in its phones -- Apple's lawyers have to show a feature was accomplished in precisely the manner described in one of its patents.

Much of Monday was spent discussing U.S. patent 5,946,647, which describes a system that detects items such as phone numbers and email addresses and provides contextual menus for them, such as "add to phone book" or "dial number."

Apple expert Todd Mowry, a computer science professor at Carnegie Mellon University, said he had spent more than 700 hours over two-and-a-half years studying Android source code for Apple -- at a rate of US$500 per hour. That would add up to more than a third of a million dollars.

He dissected the way the software interprets a finger touched on the screen, runs various subroutines that time the length of the touch, and analyzes the text on the screen underneath the finger, to determine what type of data it is and which menu options to present to the user.

His conclusion didn't come as a surprise: All nine Samsung phones accused in the case infringe the patent in question.

Attorneys for Samsung disagreed, arguing the patent specifically notes an "analyzer server" as part of the invention being claimed, and that Samsung's phones accomplish the task in a slightly different way.

Some of Apple's questions seemed to preemptively strike at one of Samsung's expected defenses: that the code in question came from Google as part of Android and wasn't developed by Samsung. Two Apple experts testified that portions of the code in Samsung phones were not the same as in Google's open-source version of Android -- although that argument doesn't necessarily prove the code didn't come from Google.

One of the most significant documents presented during the day -- one that Samsung would probably have preferred to remain secret -- was an internal Samsung user-interface road map from August 2010. It outlines proposed changes intended to make Samsung phones easier to use, and includes a change allowing items in email, such as dates, to be moved automatically to a calendar.

The Samsung document includes an image that appeared to have been lifted directly from a paper by the inventors of Apple's '647 patent that was published on the Miramontes Interactive website. The paper has been online since at least 2006.

The case, which continues on Tuesday, is 12-00630, Apple v. Samsung Electronics et al, at the U.S. District Court for the Northern District of California in San Jose.

Martyn Williams covers mobile telecoms, Silicon Valley and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is [email protected]