Error creating a new type of fit using fittype. Expression "____" is not a valid MATLAB expression, has non-scalar coefficients, or cannot be evaluated

This is what I have:

myfittype=fittype('a*exp(b*x)cos(c*x)',...
    'dependent',{'y'},'independent',{'x'},...
    'coefficients',{'a','b','c'})
f2=fit(xo,Vox,myfittype)
figure
plot(f2,xo,Vox)

This is the error I get:

Error using fittype/testCustomModelEvaluation
(line 12)
Expression a.*exp(b.*x)cos(c.*x) is not a valid
MATLAB expression, has non-scalar coefficients,
or cannot be evaluated:
Error in fittype expression ==>
a.*exp(b.*x)cos(c.*x)
??? Error: Unexpected MATLAB expression.

Error in fittype>iCreateFittype (line 371)
    testCustomModelEvaluation( obj );

Error in fittype (line 328)
                obj = iCreateFittype( obj,
                varargin{:} );

Error in VelocidadE2P2 (line 58)
myfittype=fittype('a.*exp(b.*x)cos(c.*x)',...

Caused by:
    Error using fittype/evaluate (line 102)
    Error in fittype expression ==>
    a.*exp(b.*x)cos(c.*x)
    ??? Error: Unexpected MATLAB expression.

Does anyone know? Please help

Answer 1

[Walter Roberson]

a*exp(b*x)cos(c*x)

has no operation between (b*x) and cos(c*x)

MATLAB does not have implicit multiplication.