[Scilab-users] fsolve including linear interpolation

[paul.carrico at free.fr]

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)
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