# Difference between revisions of "Talk:Controlled supply"

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Each of the values is based on the actual number of satoshi rewarded per block. This reward halves every 210,000 blocks.[https://github.com/bitcoin/bitcoin/blob/master/src/main.cpp#L1179] This halving presents a potential point of confusion; at some point the reward would be 610,351.5 satoshi - which at {{as of|2015|04|04}} cannot exist in the satoshi client's fixed point arithmetic limit.<br /> | Each of the values is based on the actual number of satoshi rewarded per block. This reward halves every 210,000 blocks.[https://github.com/bitcoin/bitcoin/blob/master/src/main.cpp#L1179] This halving presents a potential point of confusion; at some point the reward would be 610,351.5 satoshi - which at {{as of|2015|04|04}} cannot exist in the satoshi client's fixed point arithmetic limit.<br /> | ||

The value is, instead, truncated to 610,351 satoshi. The total number of satoshi generated during that reward era is thus not <tt>210,000 * 610,351.5 = 128,173,815,000 (<span class="btc">BTC</span>1,281.73815000)</tt>, but <tt>210,000 * 610,351 = 128,173,710,000 (<span class="btc">BTC</span>1,281.73710000)</tt>. The same problem presents itself with any subsequent reward eras .<br /> | The value is, instead, truncated to 610,351 satoshi. The total number of satoshi generated during that reward era is thus not <tt>210,000 * 610,351.5 = 128,173,815,000 (<span class="btc">BTC</span>1,281.73815000)</tt>, but <tt>210,000 * 610,351 = 128,173,710,000 (<span class="btc">BTC</span>1,281.73710000)</tt>. The same problem presents itself with any subsequent reward eras .<br /> | ||

− | An earlier version of the table in this page had a single satoshi error in some of the values, likely due to related floating point accuracy issues. | + | An earlier version of the table in this page had a single satoshi error in some of the values, likely due to related floating point accuracy issues.[http://www.reddit.com/r/Bitcoin/comments/31g89l/rounding_error_in_the_wiki/] |

At the actual last round there should be a total of <tt><span class="btc">BTC</span>20,999,999.97690000</tt>.<br /> | At the actual last round there should be a total of <tt><span class="btc">BTC</span>20,999,999.97690000</tt>.<br /> |

## Revision as of 22:03, 4 April 2015

## Do not Resurrect That Stupid Graph

Please see my points over at File_talk:Total_bitcoins_over_time_graph.png which describe why I deleted the graph, and description of a suitable alternative. Seriously, the amount of misleading information that prior graph has disseminated into the public is horrorshow-enormous. Midnightmagic (talk) 07:11, 14 September 2014 (UTC)

## Actual Supply is Different From The Tables Here

Note that the actual supply is different than what is listed on these graphs due to provably destroyed coins, duplicate coinbase, and underpays; this should be accounted-for in the graphs. Midnightmagic (talk) 16:32, 16 September 2014 (UTC)

## Projected Bitcoins (Long Term) - the numbers

The Projected Bitcoins Long Term table in the page uses Bitcoin unit representation as a floating point number with an 8-digit precision to convey the actual number in satoshi, which has an integer representation inside the satoshi client.

Each of the values is based on the actual number of satoshi rewarded per block. This reward halves every 210,000 blocks.[1] This halving presents a potential point of confusion; at some point the reward would be 610,351.5 satoshi - which at As of 4 April 2015^{[update]} cannot exist in the satoshi client's fixed point arithmetic limit.

The value is, instead, truncated to 610,351 satoshi. The total number of satoshi generated during that reward era is thus not `210,000 * 610,351.5 = 128,173,815,000 (BTC1,281.73815000)`, but `210,000 * 610,351 = 128,173,710,000 (BTC1,281.73710000)`. The same problem presents itself with any subsequent reward eras .

An earlier version of the table in this page had a single satoshi error in some of the values, likely due to related floating point accuracy issues.[2]

At the actual last round there should be a total of `BTC20,999,999.97690000`.

If using floating point math throughout, depending on the accuracy and behavior of the floating point calculations, this could end up being calculated as `BTC20999999.99877760`, or a difference of `BTC0.02187764`.

The floating point math approach will tend toward a total supply of `BTC21,000,000`, and a difference from the actual current maximum of `BTC0.0231`.

For technical purposes, the total supply should be noted as `BTC20,999,999.97690` with a reminder that this depends on the current fixed point arithmetic. For colloquial use, `BTC21,000,000` should be acceptable. TheRealSteve (talk) 22:01, 4 April 2015 (UTC)