Change exp from number to e

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Gregorio Garza Treviño
回答： Paul 2022-9-19
Ran in:
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

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采纳的回答

Rik
Rik 2022-9-19
Ran in:
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).

更多回答（1 个）

Paul
Paul 2022-9-19
Ran in:
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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