You vowed to love one another until death do you part, and now a calculus equation can tell with 94 percent accuracy if you'll be able to keep that promise--or not.

That's the word from University of Washington emeritus psychology professor Dr. John Gottman, who claims the calculus equation he developed can not only tell if a relationship will last, but also when the split will occur if it's doomed to fail. His extensive research over many years has produced a stunning conclusion: Couples will not be compatible 69 percent of the time.

It's not mathematical hocus-pocus. "This isn't just some parlor trick," Gottman told The Seattle Times. "The math model gave us a scientific theory for understanding relationships." He developed the formula after observing 700 couples over a period of 14 years. Gottman claims he can apply the formula to any couple after just a 15-minute videotaped interview.

During that quarter-hour session, he watches couples closely as they discuss problem topics. The calculus formula is based on an index that measures facial expression, voice tone and speech content, all of which is a characterization of the emotions each person expresses. Positive signals, such as a warmhearted joke or sympathetic nod, get points, but negative signals, such as disdainful eye-rolling or snide comments result in points lost. Specifically, Gottman is looking for such positive signs as interest, validation, affection, humor and joy, while the negative signs are seen in disgust, contempt, belligerence, domineering, anger, fear, tension, defensiveness, whining, sadness and stonewalling.

What matters isn't so much what the couples say to each other as how they say it. By keeping track of the positive and negative signals, or codes, the team was able to see a pattern emerge in the happiest and least happy marriages. The happy couples speak almost in one voice because they are so tuned into each other's wants and desires, while unhappy couples not only have no symmetry or respect for one another, but also are so nasty and mean they actually struggle to find positive things to say about one other and their relationship.

How do you turn psychology into calculus? UW applied mathematician Kristin Swanson wondered the same thing, but she admitted to the Times, "At first I thought it was ridiculous to try to translate something as ethereal as a human relationship into numbers. But I really can't quibble with over 90 percent accuracy."

--From the Editors at Netscape