Irish fiddler Eileen Ivers has been six credits shy of a master's degree for quite a while.

Originally lured away from finishing her studies by demand for her abilities on the violin, she has made an effort over the years to finish the advanced degree. The only catch is that performing on stage every night doesn't exactly keep the classwork fresh in her mind, particularly since it was not a music degree Ivers was after - it was a master's in mathematics.

The two paths are intertwined, however. Ivers, who returns to Decatur on Sunday afternoon to perform at the Kirkland Fine Arts Center, sees a deep link between her original study and her eventual career as a Celtic music innovator.

"Absolutely one of the best bits of advice I ever got was in college," she said. "The professor told me, ‘You can go anywhere in life with a math degree,' and he was right. Music and math totally go hand in hand. Writing music is like a pure expression of the elegance of math."

All arithmetic aside, it's not as if the world-renowned fiddler comes on stage with an abacus and a blackboard. She and her band, Immigrant Soul, are known for their fusion of traditional Celtic instrumentation and influences with a number of other world styles, including the seemingly odd choices of American soul and funk. Much of this influence comes in the form of band member Tommy McDonnell, a former member of the Blues Brothers Band who Ivers refers to as "the blue-eyed soul of Irish music."

"We absolutely love traditional music, and it's a big part of the show, but because of Tommy's voice, we found our group lent itself to rootsier music and soul songs," Ivers said. "Traditional players all feel the weight of responsibility to pass down the original songs in a pure, undiluted way, but we also embrace innovation at the same time with our other work. And it goes both ways: Over in Ireland the young players are making fresh sounds with influences from America to Canada."

Decatur audiences may remember Ivers' last stop at Kirkland in 2004, when Immigrant Soul was newly formed. The fiddler said to expect more of the same, as she mixes up her Celtic tunes with fusion styles from around the globe.

She has along with her the collection of electric blue fiddles that have become her visual trademark on stage, as well as a mix of other violins with a range of tones.

"I personally love a varied concert," she said. "In Decatur, we'll probably mix it up with a bluegrass set and a French Canadian set, and pull from other Celtic nations like Brittany, as well.

"Playing violin has made it very easy for me to collaborate with other artists from different genres, because the violin lends itself to so many styles. It's certainly something you can keep learning forever."

The band is working on the long-awaited follow-up to its debut album from 2003. "Beyond the Bog Road" will highlight the evolution of Celtic music in each country and culture along the Irish diaspora.

"It's about the journey of the Irish immigrant and how the music was changed at each stop along the way," Ivers said. "It's a little bit more rootsy, and it makes stops in Canadian styles and in Appalachia and others. It shows how, in certain ways, the Celtic music traditions are part of the foundations of tons of styles, even American country music today."

In her album and as a live act, Ivers is an ambassador for her instrument and the culture that was her birthright. She doesn't seem to care what kind of audiences she gets to play in front of, or mind that some audiences only seem interested in the month surrounding St. Patrick's Day. She just takes advantage of the opportunity.

"I truly feel it's such a blessing to represent your culture, no matter the time of year," Ivers said. "I embrace that challenge of getting out there and trying to expand some minds on what Celtic music can be. It's very honest, emotional and heartbreaking music at times, but more than anything, it's pure joy."