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## Description
We want to use this feature in [Akash Network](https://akash.network/).
The [Akash whitepaper](https://whitepaper.io/document/632/akash-network-whitepaper) defines a time-based function for the inflation: `I(t)`. The way `cosmos-sdk` currently calculates inflation is different as compared to what the Akash whitepaper prescribes. So, we need the `cosmos-sdk` to accept a custom function to calculate inflation. When the custom function isn't provided, it should use the default inflation calculation logic as it currently does.
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---
### Author Checklist
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I have...
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### Reviewers Checklist
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I have...
- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed
- [ ] reviewed state machine logic
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- [ ] manually tested (if applicable)
Arijit Das
Alexander Bezobchuk
Adam Bozanich
dauTT
Marko
Federico Kunze