where the expression between bars on the right-hand side is the magnitude of the cross product of the partial derivatives of x("s", "t").
w ɛ ɹ WORD_BOUNDARY ð ɪ WORD_BOUNDARY ɛ k s p ɹ ɛ ʃ ə n WORD_BOUNDARY b ɪ t w iː n WORD_BOUNDARY b ɑ ɹ z WORD_BOUNDARY ɔ n ð ə WORD_BOUNDARY ɹ aɪ t h æ n d WORD_BOUNDARY s aɪ d WORD_BOUNDARY ɪ z WORD_BOUNDARY ð ə WORD_BOUNDARY m æ ɡ n ɪ t uː d WORD_BOUNDARY ʌ v ð ə WORD_BOUNDARY k ɹ ɔ s WORD_BOUNDARY p ɹ ɑ d ʌ k t WORD_BOUNDARY ʌ v ð ə WORD_BOUNDARY p ɑ ɹ ʃ ə l WORD_BOUNDARY d ɪ ɹ ɪ v ə t ɪ v z WORD_BOUNDARY ʌ v WORD_BOUNDARY ɛ k s WORD_BOUNDARY ɛ s WORD_BOUNDARY t iː WORD_BOUNDARY