Andrzej Borucki

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since Aug 24, 2013
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Recent posts by Andrzej Borucki

I heard about it,but can't find by Google: humans created only application skeleton which was automatically filled by Java code based on Github samples. Where can I find by Google?
2 weeks ago

Zach Rode wrote:So I might be misunderstanding your question but why don't you return a collection or array? Those can contain objects or primitives(collections autoboxes primitives to their object type, just fyi)



and if I wanna returns Matrix+Matrix +int? it simply Object[] sm_block_partition() ?
6 months ago
How to deal with the elegant way of returning many variables. No pointers, no parameter reference, no make_pair.
Sample:
package sparse;

here is code moved from C++


visit_col must fill row visited and cols_visited
sm_block_partition must returns two objects;

better is return object with two or three objects or additional methods like return_last_computed_by_other_method_rows_visited ?
6 months ago
I have big C++ program which can't rewrite to Java.
This program must works with HBase.
HBase has nice Java interface, uses many *.jar's distributed by HBase.
How to use Java classes like shared library?
Reverse situation : Java using C is more popular by JNI.
This situation is also JNI? How do it? Where are examples (github?)
7 months ago
I make test million quartic equations in C++,C# nad Java: https://github.com/borneq/quartic
On Intel I3, one thread, release C++ and C#, beyond IDE,
C++ 5.99 s
C++ 64 bits 4.91 s.
C# - 5.12
Java 2.64 s!
Why Java time is so good? C++ operates on stack without new/delete, floating-point operations depends on hardware (coprocessor), the same Complex lib.
Java is the base for numeric? Unfortunately Java has not operators overloading, that is nice for complex, vectors and matrices.
10 months ago
I want compile https://github.com/mapsme/api-android/blob/master/sample-app-capitals/build.gradle and I must use Gradle.
In https://gradle.org/install/ I see: $ scoop install gradle
but how install scoop?
in http://scoop.sh/ I see: iex (new-object net.webclient).downloadstring('https://get.scoop.sh')
but not iex, I can't install Powershell because can't install Windows6.1-KB2506143-x64.msu
1 year ago
"sudo" in title is error
1 year ago
For example : export JAVA_HOME=/usr/local/jdk1.8.0_144
but my java -version is

$ java -version
openjdk version "9-internal"
OpenJDK Runtime Environment (build 9-internal+0-2016-04-14-195246.buildd.src)
OpenJDK 64-Bit Server VM (build 9-internal+0-2016-04-14-195246.buildd.src, mixed mode)


$ which java is simple: /usr/bin/java
link to Java is : /usr/lib/jvm/java-1.9.0-openjdk-amd64/bin/java

JAVA_HOME will be /usr/lib/jvm/java-1.9.0-openjdk-amd64 or /usr ?
1 year ago
How determine from Java is system (Linux) is 32 or 64 bit?
1 year ago
I see JNI is usable with DLL. I must use it with (maybe) static and C++ with mangled names. I want call LLVM low level virtual machine methods and types from Java.
1 year ago
We have large files, which not fit in memory. There exists b+-tree indexes. But finding record require big file seek. One seek is not equivalent 4 kiB block - seek has 10 millisecond of time. whereas speed of reading is 50 MB/s therefore one seek takes time as reading 500 kB. Event more - better for mechanic disc is reading continuous data than seeking.
For example: Bitcoin blocks has 100 GB of data, 200 millions transactions, 500 millions inputs + 500 millions outputs =  one billion scripts.
assume, we not use database system, but working on file system and algorithms: 200 mln transactions are indexes, now we must fin d addresses of inputs: each input has no address but has link to transaction. We must do 500 mln seeks = take time as reading 250 TB data (!) instead "only" 100 GB od data.
Which idea to decrease seek count? Maybe delayed using of found transaction, to accumulate 1000 transactions near one other?
How to make profit from memory cache? In memory can be 1%, 10%,50% of big file. Naive seek not distinguish if is more than one record in memory.
2 years ago
In Eclipse on Windows is OK, but on Ubuntu I must set: /usr/lib/jvm/java-8-openjdk-amd64/jre/lib/rt.jar
and Eclipse not compile "enum" keyword:

but thinks, it is interface
Is any Java library for .Ini files?, eq:

[mySQL]
connection=tcp://1.2.3.4:3306
user=root
password=pass
database=db
table=tab

2 years ago