I dont get why I am encountering an error message when running this code.

I want to find the integral for a function with variable limit and plot it.

This is the error I get:

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 integralCalc/vadapt (line 132)

[q,errbnd] = iterateScalarValued(u,tinterval,pathlen);

Error in integralCalc (line 75)

[q,errbnd] = vadapt(@AtoBInvTransform,interval);

Error in integral (line 87)

Q = integralCalc(fun,a,b,opstruct);

Error in rough>@(x)integral(@(t)v_t*(1-exp(expo1)+v_i*(1+exp(expo2)))./(v_t*(1+exp(expo1))+v_i*(1-exp(expo2))),1,x) (line 6)

ln_scalar = @(x)integral(@(t)v_t*(1-exp(expo1)+v_i*(1+exp(expo2)))./(v_t*(1+exp(expo1))+v_i*(1-exp(expo2))),1,x);

Error in rough>@(x)arrayfun(ln_scalar,x) (line 7)

ln = @(x)arrayfun(ln_scalar,x);

Error in rough (line 9)

plot(x,ln(x))

%v_t=20;
%v_i=1;
%g=10;
%expo1=-2*g*t./v_t;
%expo2=-2*g*t./v_i;
%function I want to integrate and plot:v_t*(1-exp(expo1)+v_i*(1+exp(expo2)))./(v_t*(1+exp(expo1))+v_i*(1-exp(expo2)))

%My code:
v_t=20;
v_i=1;
g=10;
expo1=-2*g*t./v_t;

Unrecognized function or variable 't'.

expo2=-2*g*t./v_i;
ln_scalar = @(x)integral(@(t)v_t*(1-exp(expo1)+v_i*(1+exp(expo2)))./(v_t*(1+exp(expo1))+v_i*(1-exp(expo2))),1,x);
ln = @(x)arrayfun(ln_scalar,x);
x = linspace(0.02,10,100);
plot(x,ln(x))

[Rik]

The code you posted will not run because you didn't define t yet.

Answer 1

[VBBV]

%v_t=20;
%v_i=1;
%g=10;
%expo1=-2*g*t./v_t;
%expo2=-2*g*t./v_i;
%function I want to integrate and plot:v_t*(1-exp(expo1)+v_i*(1+exp(expo2)))./(v_t*(1+exp(expo1))+v_i*(1-exp(expo2)))

%My code:
v_t=20;
v_i=1;
g=10;
t = 2;
expo1=-2*g*t./v_t;
expo2=-2*g*t./v_i;
ln_scalar = @(x)integral(@(t) v_t*(1-exp(expo1)+v_i*(1+exp(expo2)))./(v_t*(1+exp(expo1))+v_i*(1-exp(expo2))),1,x,'ArrayValued',1);
ln = @(x)arrayfun(ln_scalar,x);
x = linspace(0.02,10,100);
plot(x,ln(x))

[VBBV]

Define t first before evaluating integral

t = 2;

and set Arrayvalued option to true in integral function

ln_scalar = @(x)integral(@(t) v_t*(1-exp(expo1)+v_i*(1+exp(expo2)))./(v_t*(1+exp(expo1))+v_i*(1-exp(expo2))),1,x,'ArrayValued',1);