Change exp from number to e

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Gregorio Garza Treviño
Gregorio Garza Treviño on 19 Sep 2022
Answered: Paul on 19 Sep 2022
Im doing a little work on matlab and Im trying to type some expressions that include the number e. However, when I do this, instead of putting the e, it puts a fraction that aprroximates the value. Does anyone know how to change this?
syms c1 c2 y(x) f(x)
y(x) = (exp(2)/(exp(2)+1))*exp(-x)+(1/(exp(2)+1))*exp(x)
y(x) = 
ans = y(0)
ans = 
And as you can see, this causes it to not give an exact answer, y(0) should be 1, when it instead gives a really close approximation

Accepted Answer

Rik
Rik on 19 Sep 2022
Your own suggestion actually works (although it requires a call to simplify):
syms c1 c2 y(x) f(x) e
y(x) = (e^2/(e^2+1))*e^(-x)+(1/(e^2+1))*e^x
y(x) = 
y=simplify(y)
y(x) = 
y(0)
ans = 
1
You can also use subs to substitute e with exp(1).

More Answers (1)

Paul
Paul on 19 Sep 2022
Use sym arguments to exp, otherwise it reverts to the base Matlab numerical function.
syms c1 c2 y(x) f(x)
y(x) = (exp(sym(2))/(exp(sym(2))+1))*exp(-x)+(1/(exp(sym(2))+1))*exp(x)
y(x) = 
Evaluate at some values
simplify(y([0 1 2]))
ans = 
vpa(ans) % etc.
ans = 

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