Missing solution for exponential equation - Printable Version +- HP Forums (https://www.hpmuseum.org/forum) +-- Forum: HP Calculators (and very old HP Computers) (/forum-3.html) +--- Forum: HP Prime (/forum-5.html) +--- Thread: Missing solution for exponential equation (/thread-11506.html)

Missing solution for exponential equation - rushfan - 10-01-2018 11:45 PM The peak response of an underdamped second order system is: Mpt = 1 + e^((-z*pi)/sqrt(1-z^2)) Where Mpt is real. For Mpt = 5, the command: solve( 5 = 1 + e^((-z*pi)/sqrt(1-z^2)) ,z) Returns: Which is only the negative result. The same happens in the Solve app, I only get the negative result. The same code in matlab: clc; syms z; eqn = 5 == 1+ exp((-z*pi)/sqrt(1-z^2)); vpa(solve(eqn,z)) produces: ans = 0.40371275194342068038575605143555 -0.40371275194342068038575605143555 RE: Missing solution for exponential equation - chromos - 10-02-2018 01:02 AM Try both answers from matlab in your expression. :-) RE: Missing solution for exponential equation - Albert Chan - 10-02-2018 03:02 AM What is inside e^(...) must be positive, so (-z*pi)/sqrt(1-z^2) > 0, this imply z < 0 Matlab positive z is a mistake. (Probably just return solved quadratic roots) RE: Missing solution for exponential equation - parisse - 10-02-2018 05:36 AM Xcas 1, Matlab 0 :-)