I have a data:
data = {{1504., 0.38623}, {1698.56, 1.70795}, {1855.34, 4.77922}, {1998.22,
9.76965}, {1957.13, 7.34756}, {1924.72, 5.8017}, {1793.82,
2.84449}, {1679.68, 1.14792}, {1604.06, 0.765434}, {1422.63,
0.183902}, {1350.57, 0.078183}}
And I wanted to fit function
nlm = NonlinearModelFit[data, $\frac{c1}{Exp \left[\frac{c2 \left(\frac{3*10^8}{583.92*10^{-9}}\right)}{x+273.15}\right]-1}$, {c1, c2}, x]
I get warning: ...is too small to represent as a normalized machine number; precision may be lost.
How to fit this function?
NonlinearModelFit
rather than the display format currently showing and decide if the data set isdata
ordata8
. $\endgroup$1/Exp[750.]
underflows, I'm not surprised, given the argument in your model. You might consider giving starting values, esp. forc2
. $\endgroup$c2
works. But it is simpler if you usec1/(Exp[c0 /(x + 273.15)] - 1)
as the model and then solve for the appropriate multiple ofc0
to getc2
because the default starting values work fine in that case. $\endgroup$