# Find limit of Interpolated function

I have an interpolated function

f = Interpolation[data]

I would like to calculate limits such as

Limit[(f[1.5 + h] - f[1.5])/h, h -> 0]

I just get errors.

• That's just the derivative you want; try f'[1.5]. – J. M. is in limbo May 31 '13 at 1:58
• Limit is a purely algebraic tool. You could try NLimit from the NumericalCalculus package. I concur with J.M., however, that your specific example would be best approached with f'. – Mark McClure May 31 '13 at 2:04
• I know it's the derivative. I want my students to find a derivative with a limit. – user7716 May 31 '13 at 2:16
• In general, interpolated functions seem fussy compared to user defined functions. – user7716 May 31 '13 at 2:16
• While I agree it might be a reasonable thing to do, at this time Limit is not going inside the InterpolatingFunction to extract a local interpolant polynomial. – Daniel Lichtblau May 31 '13 at 3:12

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