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Why doesn't fittype, in the curve fitting toolbox, see independent variable in input list of called function?

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Larry
Larry 2016-9-2
评论： RAJEEV 2023-1-27
I want to use a fit model in the curve fitting toolbox complicated enough to warrant an m-file, but can't get fittype to recognize the independent variable. The same error is generated using the simple function given in the Help example:
>> g = fittype( @(a, b, c, x) a*x.^2+b*x+c )
g =
General model:
g(a,b,c,x) = a*x.^2+b*x+c
Suppose I name the model function:
>> f=@(a,b,c,x) a*x.^2+b*x+c
f =
@(a,b,c,x)a*x.^2+b*x+c
It evaluates nicely:
>> f(1,1,1,1)
ans =
3
but throws an error in fittype:
>> fittype( @(a, b, c, x) f)
Error using fittype>iAssertIsMember (line 1082)
*Independent variable x does not appear in the equation expression.*
Error in fittype>iTestCustomModelParameters (line 728)
iAssertIsMember( obj.indep, variables, 'curvefit:fittype:noIndependentVar' );
Error in fittype>iCreateFittype (line 370)
iTestCustomModelParameters( obj );
Error in fittype (line 328)
obj = iCreateFittype( obj, varargin{:} );
Naming the independent variable:
>> fittype( @(a, b, c, x) f,'independent','x')
gives the same error.
An m-file also gives the same error. I delete f, save f.m containing:
function ff = f(a,b,c,x)
ff = a*x.^2+b*x+c;
and execute:
>> fittype( @(a, b, c, x) f,'independent','x')
and get the same error as above.

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回答（2 个）

Steven Lord
Steven Lord 2016-9-2
See my response to your posting of this question in the newsgroup.
Larry
Larry 2016-9-2
编辑：Matt J 2016-9-2
fittype( @(a, b, c, x) f *(a,b,c,x)*)
works w/ f.m.

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