Input function must return 'double' or 'single' values. Found 'sym'.

When i use the integral command i get the following error, even though i defined all of the variables:

Error using integralCalc/finalInputChecks

Input function must return 'double' or 'single' values. Found 'sym'.

Error in integralCalc/iterateScalarValued (line 315)

finalInputChecks(x,fx);

.

.

.

Error in int (line 24)

f4 = (1/(t-s^4))*(rho_w_ad+t_w_ad*((x/(t-s))^2-0.5))*exp(-(x/(t-s))^2);

where rho_w_ad, t_w_ad:

syms t s x

alpha = 20;

h = 1;

rho_in = 0;

T_in = exp(-alpha*(s-h));

% this is the first integral

f1 = s*(rho_in*((s^2)/(t^2)-5)+T_in*((s^4)/(t^4)-(11*(s^2))/(2*(t^2))+3.5))*(exp(-s^2/t^2));

firstFunc = matlabFunction(f1);

rho_w_ad = @(t) integral(@(s) firstFunc(s,t) , 0,inf)*(1./t.^2.*(-1./2));

% this is the second integral

f2 = s*(rho_in*((s^2)/(t^2)-1)+T_in*((s^4)/(t^4)-(3*(s^2))/(2*(t^2))+1.5))*(exp(-s^2/t^2));

secondFunc = matlabFunction(f2);

t_w_ad= @(t) integral(@(s) secondFunc(s,t) , 0,inf)*(1./t.^2);

% f4 is further down

what am i doing wrong?

Answer 1

[Torsten]

rho_w_ad and t_w_ad are functions of t. So you will have to define

f4 = @(t,x,s) (1./(t-s.^4)).*(rho_w_ad(t)+t_w_ad(t).*((x./(t-s)).^2-0.5)).*exp(-(x./(t-s)).^2);

Answer 2

[Marcel]

Have you tried double(yourVarHere) ?

This way you can convert your variable to the expected double and you could try if this fixes your issue. You have to convert the correct variable tho