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From: awu on 7 Aug 2010 02:30
Dear all
I used the bellow commands in the command window but I have a problem for using dblquad.
I dont know the wrong point.
Someone who know how handle this problem please suggest me.
Thanks for any help

>> syms x y z;
>> fa=5000;
>> ht=2/fa;
>> syms dzdx dzdy;
>> dzdx=2*ht*fa/pi*(cos(x*fa)*cos(y*fa)+(cos(3*x*fa)*cos(3*y*fa))/3)

dzdx =

5734161139222659/4503599627370496*cos(5000*x)*cos(5000*y)+1911387046407553/4503599627370496*cos(15000*x)*cos(15000*y)


>> dzdy=2*ht*fa/pi*(sin(x*fa)*sin(y*fa)+(sin(3*x*fa)*sin(3*y*fa))/3)

dzdy =

5734161139222659/4503599627370496*sin(5000*x)*sin(5000*y)+1911387046407553/4503599627370496*sin(15000*x)*sin(15000*y)


>> Q = dblquad(@(x,y)sqrt(dzdx^2+dzdy^2+1), 0, 2*pi/fa, pi/2/fa, 5*pi/2/fa)

??? Error using ===> innerintegral
Inputs to innerintegral must be floats, namely single or
double.

Error in ==> dblquad>innerintegral at 81
Q = zeros(size(y), superiorfloat(fcl, xmax, y));

Error in ==> quad at 77
y = f(x, varargin{:});

Error in ==> dblquad at 60
Q = quadf(@innerintegral, ymin, ymax, tol, trace, intfcn, ...
From: Bruno Luong on 7 Aug 2010 04:29
dblquad is *numerical* integration, it is not supposed to work with symbolic objects (function handle should return value).

Bruno
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