In[]:=
a=10​​
ψ
1
[x_]=Piecewise[{{17.9/Sqrt[a]*Exp[3.8*2*x/a],x<-a/2},{1.26/Sqrt[a]*Cos[2.5*x/a],-a/2≤x≤a/2},{17.9/Sqrt[a]*Exp[-3.8*2*x/a],x>a/2}}]
Out[]=
10
Set
:Tag Piecewise in
5.66048
0.76x

x<-5
0.398447Cos[0.25x]
-5≤x≤5
5.66048
-0.76x

x>5
0
True
[x_] is Protected.
Out[]=
5.66048
0.76x

x<-5
0.398447Cos[0.25x]
-5≤x≤5
5.66048
-0.76x

x>5
0
True
In[]:=
Plot[Piecewise[{{5.66048
0.76x

,x<-5},{0.398447Cos[0.25x],-5≤x≤5},{5.66048
-0.76x

,x>5}},0],{x,-84.823,84.823}]
Out[]=