Conversion to double from sym is not possible

Hi every body,

this is my code

syms t

x=-3:.1:3;

for i=1:length(x);

    Pin=3*exp(-t^2);

    z=x(i);

    Eo(i)=int(Pin,t,-inf,z);

    Ein(i)=int(Pin,t,-inf,inf);

    E(i)=Eo(i)/Ein(i);

    Go=1000;

    G(i)=Go/(Go-(Go-1)*exp(-E(i)*0.1));

    Bc=3;

    Dv(i)=-(Bc*Pin/(4*pi*10*Ein(i)))*(G(i)-1);

end

plot(x,Dv,'-r*')

when I come to plot, I get this message

Conversion to double from sym is not possible

help me please, have a nice life

[Andrei Bobrov]

Pin use in last row, so Pin(x)?

Answer 1

[Andrei Bobrov]

variant with use Symbolic Toolbox ( MATLAB R2010a )

x = -3:.1:3;
syms t
Ein = int(3*exp(-t^2),-inf,inf);
Eo0 = int(3*exp(-t^2),-inf,x(1));
E = (Eo0 + int(3*exp(-t^2),t,x(1),t))/Ein;
Dv = matlabFunction(eval((9*exp(-t^2)/(40*pi*Ein))*(1000/(1000-999*exp(-E*0.1))-1)));
plot(x,Dv(x),'-r*')

varint numeric

x = -3:.1:3;
f = @(z)3*exp(-z.^2);
Ein = quadgk(f,-inf,inf);
Eo0 = quadgk(f,-inf,x(1));
Dv1 = arrayfun(@(x)quadgk(f,-inf,x),x);
Dv = (3*f(x)/(40*pi*Ein)).*(1000./(1000-999*exp(-(Eo0+Dv1)/Ein*0.1))-1);
plot(x,Dv,'k-+')

Answer 2

[Walter Roberson]

Try

Dv(i) = double( -(Bc*Pin/(4*pi*10*Ein(i)))*(G(i)-1) );