Delivering a master class in showmanship, Keisha Patterson left the audience at last weekend’s Jazz in the Gardens show lustily applauding. Her velvety smooth vocals throughout a six-song set, which included such perennial gems as Nancy Wilson’s How Glad I Am and Antônio Carlos Jobim’s One Note Samba, so entranced the audience that Patterson was greeted with effusive praise and a series of handshakes in the lobby of The Jamaica Pegasus hotel from earnest admirers after putting down the microphone.