PROVIDENCE - Joni Mitchell performed to a near- capacity crowd at the Civic Center last night. Mitchell achieved stardom in the early '70s with five albums of folk-pop. Her greatest success came with her sixth LP, "Court and Spark," in 1974.

That album also established Mitchell's growing interest in jazz. That jazz feeling has become more dominant over the last five years and five albums, culminating in the recent release of "Mingus," a collection of collaborations between the singer and jazz great Charles Mingus.

The difference between Mitchell's two styles has divided her audience. Some have embraced the new work, citing its boldness and Mitchell's courage in pursuing a commercially shaky course. Others have felt that the composer should not have abandoned a style at wich she was a master in order to begin again as a novice in a field already full of unrecognized genius. The audience at the Civic Center did not know what to expect, and if Joni Mitchell did not completely make peace between her two aspects, at least she tore down a few barriers.

The program was opened by the Persuasions, an a capella group. Some of their nightclub stage patter seemed a little out of place in the large arena, but at their best the Persuasions' exciting harmonies and relaxed style were a lot of fun.

Mitchell began her performance with a barrage of her best known material, as if to calm any fears that she had ventured too far "outside" in her new pursuits. "Big Yellow Taxi," "This Train," "In France They Kiss on Main Street" and "Free Man In Paris" pleased the audience, but seemed to lack a certain spark. Perhaps Mitchell's heart was not in it, or perhaps it just took a bit to get used to the hollow, booming sound of the Civic Center. Mitchell's band was a who's who of jazz fusion greats: Jaco Pastorius, Pat Metheny, Michael Brecker, Don Alias and Lyle Mays. The songs were performed well, but seemed almost aimless.

Mitchell straightened that out with her rendition of "Goodbye, Pork Pie Hat," a Mingus composition well suited to the talents of her distinguished ensemble. It was a beautiful, restrained performance that pulled real emotion from the familiar melody. Her rendering went a long way toward establishing that Joni Mitchell can be a jazz singer.

The rest of the show pretty much followed the pattern established early on. There were slow stretches when it was apparent that Mitchell's is still very much a talent in transition - a talent struggling to incorporate a lot of ideas into an unfamiliar form. But these stretches were broken by bursts of real excitement when all the ideas came together and really worked.

As the show finished, the high points came closer together. A real hot "Raised on Robbery" proved once again that no one can rock like a slumming jazz musician. The Persuasions came back out to join Mitchell for a gorgeous "Shadows and Light." The ovation was one of the greatest I have ever heard and Mitchell delighted the crowd by performing her old ballad "The Last Time I Saw Richard" alone at the piano.

Then, for a real unexpected treat, as welcome for its humor as for its musical value, the Persuasions again came out to join Mitchell for a terrific rendition of the oldie "Why Do Fools Fall in Love?"

At moments like these it was obvious why Joni Mitchell's fans stick with her through all the slow stretches. The highs are so high.