- #1
msumani
- 1
- 0
We have been trying to fit experimental diffusion results to the diffusion equation using Matlab to evaluate the Diffusion coefficient.
The equation we used:
y=C*erfc(x/(2*sqrt(D*t)))
Experimental values [x],[y] and t are given. C and D are to be evaluated from the curve fit.
We used cftool of Matlab.
We have a problem in getting the results. We get error message as:
"Error using ==> <a href="error:C:\Program Files\MATLAB\R2007b\toolbox\curvefit\curvefit\@fittype\feval.m,97,0">fittype.feval at 97</a>
Error in fittype expression ==> C.*erfc(x./(2.*sqrt(D.*300)))
? Error using ==> erfcore
Input must be real."
Can anyone help?
The equation we used:
y=C*erfc(x/(2*sqrt(D*t)))
Experimental values [x],[y] and t are given. C and D are to be evaluated from the curve fit.
We used cftool of Matlab.
We have a problem in getting the results. We get error message as:
"Error using ==> <a href="error:C:\Program Files\MATLAB\R2007b\toolbox\curvefit\curvefit\@fittype\feval.m,97,0">fittype.feval at 97</a>
Error in fittype expression ==> C.*erfc(x./(2.*sqrt(D.*300)))
? Error using ==> erfcore
Input must be real."
Can anyone help?