ScalaUA 2020

I like visiting ScalaUA conference in Kiev every year in March or April. I did so in 2017, 2018 and 2019. So for 2020 it was kind of difficult to perform a regular conference. So there are two options, either it could have been cancelled or it could have been postponed. That is what all […]

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Borrow and Carry Bit for Subtraction

Similar to the usage of the carry bit when adding there are mechanisms for subtracting that allow to integrate the result of subtraction of the lower bits into the subtraction of the next higher block of bits, where necessary. There are two ways to do this, that are trivially equivalent by a simple not operation: […]

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How to draw lines, circles and other curves

These ideas were developed more than 30 years without knowing that they were already known at that time… Today the graphics cards can easily do things like this in very little time. And today’s CPUs are of course really good at multiplying. So this has lost a lot of its immediate relevance, but it is […]

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Logging

Deutsch Software often contains a logging functionality. Usually entries one or sometimes multiple lines are appended to a file, written to syslog or to stdout, from where they are redirected into a file. They are telling us something about what the software is doing. Usually we can ignore all of it, but as soon as […]

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Carry Bit, Overflow Bit and Signed Integers

It has already been explained how the Carry Bit works for addition. Now there was interest in a comment about how it would work for negative numbers. The point is, that the calculation of the carry bit does not have any dependency on the sign. The nature of the carry bit is that it is […]

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Virtual machines

We all know that Java uses a „virtual machine“ that is it simulates a non-existing hardware which is the same independent of the real hardware, thus helping to achieve the well known platform independence of Java. Btw. this is not about virtualization like VMWare, VirtualBox, Qemu, Xen, Docker and similar tools, but about byte code […]

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How to multiply long numbers

Assuming we have a multiplication of n-bit-numbers already available. Other than typical compiled languages, which assume that the multiplication result fits into the same size as the two factors, we should take a closer look. Unsigned n-bit-numbers as factors and fullfill         So we have for the product     So we […]

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How to recover the Carry Bit

As frequent readers might have observed, I like the concept of the Carry Bit as it allows for efficient implementations of long integer arithmetic, which I would like to use as default integer type for most application development. And unfortunately such facilities are not available in high level languages like C and Java. But it […]

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Restklassenrundung

English Das Konzept der Rundung kennt man grundsätzlich. Aber versuchen wir es etwas systematischer zu erfassen. Man hat eine Menge von Zahlen und eine Teilmenge davon, deren Elemente in der verwendeten Programmierumgebung dargestellt werden. Dazu hat man noch eine Metrik . Man verlangt normalerweise noch gewisse Eigenschaften von : Positive Definitheit: Symmetrie: Dreiecksungleichung: Typischerweise sind […]

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Scala Exchange 2014

English Ich war am 8. und 9. Dezember 2014 auf der Konferenz Scala Exchange ( #scalaX ) in London. Von mir besuchte Vorträge waren etwa folgende: The Binary Compatibility Challenge Martin Odersky Es gibt Beispiele von allen vier Kombinationen von Sourcecode- und Binärkompatibilität. Man wünscht sich von beidem mehr, Schwerpunkt heute aber Binärkompatibilität. Konflikt für […]

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