undefined function or variable when definition set

hello

my work space looks

'f, minusF, p1, p2, p3, p4, p5, p6, p7, p8, p9, RMSD, Sim'

however when I issue the fminbnd command I see

x = fminbnd(minusF,0,1200)
Undefined function or variable 'p9'.

Error in @(x)p1*x^8+p2*x^7+p3*x^6+p4*x^5+p5*x^4+p6*x^3+p7*x^2+p8*x+p9

Error in @(x)-f(x)

Error in fminbnd (line 215)
x= xf; fx = funfcn(x,varargin{:});

is this error caused by the workspace ordering? If so will someone corrects me or provide a link to the required order in which commands must be entered into Matlab please.

Gavin.

Answer 1

[Gavin Seddon]

Thanks, this briefly answers my long question Walter.

Answer 2

[Jan]

Has p9 been defined before creating minusF?

Please post the relevant part of the code.

Answer 3

[Walter Roberson]

You should never create a function handle that mentions something that has not already been defined. The exception is that when you define an anonymous function, in the part after the @() you can mention any variable name that appeared inside the @()

The order must be to define p1, p2, p3, p4, p5, p6, p7, p8, p9, and then you can use

f = @(x) p1.*x.^8 + p2.*x.^7 + p3.*x.^6 + p4.*x.^5 + p5.*x.^4 + p6.*x.^3 + p7.*x.^2 + p8.*x + p9;

and then you can use

minusF = @(x) -f(x)

and then you can pass minusF into fminbnd()