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gen exp_fun #876
gen exp_fun #876
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theories/exp.v
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Variable R : realType. | ||
Implicit Types a x : R. | ||
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Definition exp_fun a x := expR (x * ln a). | ||
Definition power_pos a x := if a == 0 then 0 else expR (x * ln a). |
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Within the current limitation that we cannot properly handle the complex analysis, this definition seems to be the best possible approximation to the power function on R x R. It works for 0 < r < ∞, 0 <= θ < π if seen in the polar coordinate system.
@thery Allow me to ping you in case this slipped under your radar |
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Overall looks good to me
I'll merge tomorrow if there is no more comment |
- rename to power_pow - fix doc - add scope to notation Co-authored-by: Alessandro Bruni <[email protected]> Co-authored-by: Takafumi Saikawa <[email protected]>
- so that power_pos and exprn coincide
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LGTM |
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Last changelog comments before I merge
Many thanks for the reviews! |
* gen exp_fun - rename to power_pow - fix doc - add scope to notation Co-authored-by: Alessandro Bruni <[email protected]> Co-authored-by: Takafumi Saikawa <[email protected]> * add lemma power12_sqrt * additional lemmas * change power_pos so that 0^0=1 - so that power_pos and exprn coincide * measurable_fun exp ln * fix chaneglog * add power_pos_intmul proposed by Pierre * fix changelog --------- Co-authored-by: Alessandro Bruni <[email protected]> Co-authored-by: Takafumi Saikawa <[email protected]> Co-authored-by: Alessandro Bruni <[email protected]>
Motivation for this change
We @hoheinzollern @t6s needed a bit more general version of
exp_fun
for PR #790 and PR #516(in particular to define a power function with extended reals)
Things done/to do
CHANGELOG_UNRELEASED.md
Automatic note to reviewers
Read this Checklist and put a milestone if possible.