Tutorial by Topics: gnu

GnuPG is a sophisticated key management system which allows for secure signing or encrypting data. GPG is a command-line tool used to create and manipulate GnuPG keys.

GnuPG is most widely used for having SSH (Secure Shell) connections without password or any means of interactive authentication, which improves security level significantly.

Following sections describe ways to create, use, and maintain security of GnuPG keys.

In this topic we propose a simple method to correctly design simple digital circuits with VHDL. The method is based on graphical block diagrams and an easy-to-remember principle:

Think hardware first, code VHDL next

It is intended for beginners in digital hardware design using VHDL, with a limited understanding of the synthesis semantics of the language.

A column is NULL when it has no value, regardless of the data type of that column. A column should never be compared to NULL using this syntax a = NULL as the result would be UNKNOWN. Instead use a IS NULL or a IS NOT NULL conditions. NULL is not equal to NULL. To compare two expressions where null can happen, use one of the functions described below. All operators except concatenation return NULL if one of their operand is NULL. For instance the result of 3 * NULL + 5 is null.

The fit command can fit a user-defined function to a set of data points (x,y) or (x,y,z), using an implementation of the nonlinear least-squares (NLLS) Marquardt-Levenberg algorithm.

Any user-defined variable occurring in the function body may serve as a fit parameter, but the return type of the function must be real.

Ada's standard packages provide for output of all numeric types. The format of output can be adjusted in many ways.

To quote from @SnoringFrog's topic-creation request:

"One of the biggest gotchas using sed is scripts that fail (or succeed in an unexpected way) because they were written for one and not the other. Simple run-down of the more major differences would be good."

The GNU C compiler comes with some cool features that are not specified by the C standards. These extensions are heavily used in system software and are a great tool for performance optimization.

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