[Deep learning] Gradient Descent Optimizer

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https://icim.nims.re.kr/post/easyMath/70 알기 쉬운 산업수학 알기 쉬운 산업수학 Gradient Descent Optimizer 2017년 12월 13일(수) | 김민중 URL  (1) 주어진 목적함수  f f 의 최솟값(minimum)을 찾아가는 알고리즘으로 다음과 같은 방식으로 최솟값을 찾아간다. 초기값  x 0 x 0 을 임의로 설정, 적당한 Learning rate  α α  설정 n ≥ 0 n ≥ 0 인 정수에 대해서  x n + 1 x n + 1 은 다음과 같이 정의한다. x n + 1 : = x n − α ⋅ ∇ f ( x n ) x n + 1 := x n − α ⋅ ∇ f ( x n ) 주의사항 함수 f f 의 모양이 convex가 아닌 경우 global minimum이 아닌 local minimum으로  x n x n 이 수렴할 가능성이 있다. Learning rate  α α  값이 큰 경우 최솟값으로  x n x n 이 수렴하는 것이 아니라 발산할 수 있다. Learning rate  α α  값이 작은 경우 수렴하는 속도가 지나치게 느릴 수 있다. 방정식  2 ⋅ x = 10 2 ⋅ x = 10  의 근을 Gradient Descent를 이용해서 찾아보자. 목적함수  f ( x ) : = ( 10 − 2 x ) 2 f ( x ) := ( 10 − 2 x ) 2 으로 설정하겠다( f f 의 최솟값인 0이 되게 하는  x x 값이 우리가 원하는 방정식의 근이다). 초기값  x 0 = 0 x 0 = 0 , Learning rate  α = 0.05 α = 0.05 으로 설정 f ′ ( x ) = 4 ( 2 x − 10 ) f ′ ( x ) = 4 ( 2 x − 10 ) 이므로  x 1 x 1 은 다음과 같이 구할 수 있다. x 1 = x 0 − α ⋅ f ′ ( x 0 ) = 0 − 0.05 ⋅ ( − 40 ) = 2 x
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[MS Sql server management studio] Insert BLOB


https://www.mssqltips.com/sqlservertip/1489/using-filestream-to-store-blobs-in-the-ntfs-file-system-in-sql-server-2008/

https://www.codeproject.com/Articles/128657/How-Do-I-Use-SQL-File-Stream

http://blog.ceservices.com/adding-filestream-database-sql

https://stackoverflow.com/questions/1643627/how-to-insert-a-blob-into-a-database-using-sql-server-management-studio




https://stackoverflow.com/questions/11820971/how-to-update-a-blob-in-sql-server-using-tsql/11820972#11820972




11down voteaccepted
There are two ways to SELECT a BLOB with TSQL:
SELECT * FROM OPENROWSET (BULK 'C:\Test\Test1.pdf', SINGLE_BLOB) a
As well as:
SELECT BulkColumn FROM OPENROWSET (BULK 'C:\Test\Test1.pdf', SINGLE_BLOB) a
Note the correlation name after the FROM clause, which is mandatory.
The second version can be used for a UPDATE as in the following example:
UPDATE MyTable 
SET blobField = 
   (SELECT BulkColumn FROM OPENROWSET (BULK 'C:\Test\Test1.pdf', SINGLE_BLOB) a) 
WHERE (CriteriaField = @criteria)
For partial updates one can use the SET .WRITE mutator as described in this MSDN article, here is the syntax:
UPDATE MyTable SET BlobField .WRITE (expression, @offset, @length) WHERE (CriteriaField = @criteria)
Note that the WRITE mutator can only be used on NON-NULL fields.
In fact this can also be used to do a full update (if the column does not contain NULL), by setting @offset to 0 and @length to NULL (or to the actual length), as in the following example:
DECLARE @tmp VARBINARY(MAX) --Change to the correct datatype here
SELECT @tmp = BulkColumn FROM OPENROWSET (BULK 'C:\Test\Test1.pdf', SINGLE_BLOB) a
UPDATE MyTable SET BlobField .WRITE (@tmp, 0, NULL) WHERE (CriteriaField = @criteria)
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@import' when modules are disabled

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[Iphone][build error] pngcrush caught libpng error: PNG unsigned integer out of range.

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When xcode build says " pngcrush caught libpng error: PNG unsigned integer out of range. " Reference : http://stackoverflow.com/questions/17531255/how-do-i-fix-this-copypng-file-error <In my case following solution works> Build Phases -> Copy Bundle Resources, Any fileName is red color? Or Convert Logo Retina.png or Create it again, maybe it's an encoding\format issue. Or Rename "Logo Retina.png" to "LogoRetina.png". Good luck~ share improve this answer edited  Jun 30 '15 at 10:07 Ted 5,122 3 27 45 answered  Jul 8 '13 at 17:28
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