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another fsolve question - roadrunner - 06-20-2015 04:01 PM

Can anyone tell me what I am doing wrong?

I plotted the function ph2o(X) (code below) and touched Menu/Fcn/Tangent and, as expected, I saw the tangent line at the cursor location that I could trace up and down the curve.


However, when I plot function tdew(X,15) (code also below) and touch the tangent soft-key I get nothing. When I touch slope I get NaN.


I get the same result with newton, newtonj, and bisection solver. Am I doing something wrong, or is the calculator not capable of that operation on that function?

Thanks for reading,



EXPORT ph2o(temp)
 local a,b;
 return 10^(10.79574*a-5.028*log(b,10)+

export tdew(r,tamb)
 LOCAL y,z;
 z:="fsolve(ph2o(x)="+STRING(r,2,12)+",x,−50 .. 100, newton_solver)";
 RETURN y(1);