[#wallet-SelectionResult-RecalculateWaste]
= xref:wallet.adoc[wallet]::xref:wallet/SelectionResult.adoc[SelectionResult]::RecalculateWaste
:relfileprefix: ../../
:mrdocs:

Calculates and stores the waste for this result given the cost of change and the opportunity cost of spending these inputs now vs in the future. If change exists, waste = change_cost + inputs * (effective_feerate ‐ long_term_feerate) ‐ bump_fee_group_discount If no change, waste = excess + inputs * (effective_feerate ‐ long_term_feerate) ‐ bump_fee_group_discount where excess = selected_effective_value ‐ target change_cost = effective_feerate * change_output_size + long_term_feerate * change_spend_size

== Synopsis

Declared in `<wallet/coinselection.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
void
RecalculateWaste(
    xref:CAmount.adoc[CAmount] min_viable_change,
    xref:CAmount.adoc[CAmount] change_cost,
    xref:CAmount.adoc[CAmount] change_fee);
----

== Parameters

[cols="1,4"]
|===
| Name| Description
| *min_viable_change* [in]
| The minimum amount necessary to make a change output economic
| *change_cost* [in]
| The cost of creating a change output and spending it in the future. Only used if there is change, in which case it must be non‐negative.
| *change_fee* [in]
| The fee for creating a change output
|===


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