paul.carrico |
Hi All
I'm wondering what is the way to solve the following study (but at the same time I'm not sure that the problem has been correctly posed) ... I'm a bit "disrupted" by theta scalar that depends itself on x value. The problem seems to be non linear and I tried (but I failed) in using fsolve.
Any suggestion where I've to see to?
Thanks for your time and help
Paul
#################################################
function y=calculus(x) theta = [ 1 100 200 300 1000 1200 1500 2000]'; theta_interp = interp1(theta(:,1),theta(:,2),x,'linear'); y = -theta_interp * 0.268 + 120 -x; //pause // if theta = 1 : y = 0 -> x = 120 - 0.268 = 119.73 // if theta = 100 : y = 0 -> x = 120 - 26.8 = 93.2 // if theta = 200 : x = 66.4 // if theta = 300 : x = 120 - 0.268 = 39.6 // can we say that y belongs to [39.6 , 119.73] ? endfunction [x,v,info] = fsolve(0,calculus) _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users |
roger.cormier |
Paul:
It appears that you're solving for y given theta and x, but y is a linear function of theta and x. I don't have a good knowledge of what you are trying to solve, but when I solve nonlinear problems I normally either have a form of first-order derivative (scalar or a Jacobian), or some form of branching/discontinuity from which I need to choose the "best" solution. For linear interpolation, I find that it's easier to simply write a function myself than try to figure out how to make a given built-in function works. I'm going fishing here: in your function, theta is 8x1 but your arguments for interpl are theta(:,1),theta(:,2), which presumes that theta is 8x2, so that could be a place to start looking at why fsolve is giving your grief. Regards, Roger. ______________________________________________ Dr. Roger Cormier, P.Eng. Home Tel. & Fax: 613-823-7299 Am mar. 18 avr. 2017 um 09:03 schrieb [hidden email]: > Hi All > > I'm wondering what is the way to solve the following study (but at the same time I'm not sure that the problem has been correctly posed) ... I'm a bit "disrupted" by theta scalar that depends itself on x value. > > The problem seems to be non linear and I tried (but I failed) in using fsolve. > > Any suggestion where I've to see to? > > Thanks for your time and help > > Paul > > > > ################################################# > function y=calculus(x) > > > theta = [ 1 100 200 300 > > > 1000 1200 1500 2000]'; > > > > theta_interp = interp1(theta(:,1),theta(:,2),x,'linear'); > > > y = -theta_interp * 0.268 + 120 -x; //pause > > > > // if theta = 1 : y = 0 -> x = 120 - 0.268 = 119.73 > > > // if theta = 100 : y = 0 -> x = 120 - 26.8 = 93.2 > > > // if theta = 200 : x = 66.4 > > > // if theta = 300 : x = 120 - 0.268 = 39.6 > > > > // can we say that y belongs to [39.6 , 119.73] ? > > > > endfunction > > > > [x,v,info] = fsolve(0,calculus) > > > > _______________________________________________ > users mailing list > [hidden email] > http://lists.scilab.org/mailman/listinfo/users _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users |
paul.carrico |
the example I built is not relevant and it does not reflect the problem behind... sorry for the inconvenient
Paul
Le 2017-04-18 17:20, [hidden email] a écrit :
Paul: _______________________________________________ users mailing list [hidden email] http://lists.scilab.org/mailman/listinfo/users |
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