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Basis Function: ÒSticksÓ
¥ The set of basis functions you use determines the range of possible HRFs that you can compute
¥ ÒStickÓ (or Dirac delta) functions are very flexible
H But they come with a strict limitation
¥ d(t ) is 1 at t=0 and is 0 at all other values of t
¥ yq(t ) = d(t Ðq×TR) for q=0,1,2,É,p
Þ h(0) = b0
Þ h(TR) = b1
Þ h(2 ×TR) = b2
Þ h(3 ×TR) = b3
Þ  et cetera
Þ h(t ) = 0 for any t not on the TR grid
Þ
time
h
t=0
t=TR
t=2×TR
t=3×TR
t=4×TR
t=5×TR
Each piece of h(t ) looks like a stick poking up