In[]:=
Remove["Global`*"];
In[]:=
data={{-2,1},{-1,4},{0,5},{1,3},{2,2}};​​plot1=ListPlot[data]
Out[]=
In[]:=
<<Splines`
In[]:=
sp1=SplineFit[data,Cubic]
Out[]=
SplineFunction[Cubic, {0.,4.}, <>]
In[]:=
plot2=ParametricPlot[sp1[t],{t,0,4}];​​Show[plot1,plot2]
Out[]=
In[]:=
sp1[2.5]
Out[]=
{0.5,4.12723}
In[]:=
sp2=Interpolation[data,Method->"Spline",InterpolationOrder->3]
Out[]=
InterpolatingFunction
Domain: {{-2,2}}
Output: scalar

In[]:=
sp2[0.5]
Out[]=
4.20313