The TI 89 Platinum calculator is returning ln(abs(cos(x))/abs(sin(x)-1)) for the integral of sec(x)dx, which is incorrect. The expected results are ln(abs(tan(x)+sec(x))) or ln(abs(sin(x)+1)/abs(cos(x))). Users have reported inconsistencies, such as receiving 'undefined' for x=0, which should yield 0. This discrepancy may stem from the syntax used in TI Basic for computing integrals rather than a computational error.
PREREQUISITESStudents and educators in mathematics, particularly those using the TI 89 Platinum for calculus, as well as anyone troubleshooting integral computation discrepancies on this calculator model.
I don't understand why I'm getting a "non-real result" from the calculation when I enter x=0. Why is that occurring? It should be the same regardless of which form it's written in.Baluncore said:Ln(abs(sin(x)+1)/abs(cos(x))) = Ln(abs(cos(x))/abs(sin(x)-1))
UPDATE: Just to make me look like a liar... Now my TI 89 is returning 0 for x=0... ? It was returning "Non-real result" before.jdcirbo said:My TI 89 Platinum is returning ln(abs(cos(x))/abs(sin(x)-1)) for integral sec(x)dx. It's supposed to return ln(abs(tan(x)+sec(x)) or ln(abs(sin(x)+1)/abs(cos(x))). If you enter x=0, you get 'undefined' the way my TI 89 is doing it. It's supposed to return 0. Is this a computation error or something with the syntax of how TI Basic computes integrals?