# Piecewise function and integral function

Given a piecewise function f[t_]:=Piecewise[{{Exp[-1/t^2],t>0},{0,x<=0}}], I can define another function like this: g[t_]:=f[t+1]f[1-t]. Both the functions can be calculated and plotted. But when I define the third function h[t_]:=Integrate[g[x],{x,-:inf:,t}], h[t] cannot be used to plot. Does the definition for h[t] have anything wrong?

• Please be more specific about what you mean by "cannot be used". Also: did you mean to write x <= 0 or t <= 0 in f? Commented Jan 29, 2015 at 3:46
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• Recommend that the definition of g be modified to g[t_] = f[t + 1] f[1 - t] // PiecewiseExpand // Simplify Commented Jan 29, 2015 at 5:15
• Thanks, I have revised the question. Commented Jan 29, 2015 at 7:08

You have an error in the definition of f[] and it's faster to use NIntegrate[]:
f[t_] := Piecewise[{{Exp[-1/t^2], t > 0}, {0, t <= 0}}]