---
name: "mlpack_Log"
section: "3"
platform: "linux"
package: "mlpack-doc"
version: "1.0.10-1"
release: "Debian 8 (Jessie)"
platforms: ["linux"]
url: "https://new.carta.tech/mlpack_Log"
---

# mlpack\_Log(3)

Provides a convenient way to give formatted output.

## NAME

mlpack::Log -

Provides a convenient way to give formatted output.

## SYNOPSIS

### Static Public Member Functions

static void **Assert** (bool condition, const std::string &message='Assert Failed.')\
 *Checks if the specified condition is true.*

### Static Public Attributes

static std::ostream & **cout**\
 *Reference to cout, if necessary.*  static **util::NullOutStream** **Debug**\
 *Dumps debug output into the bit nether regions.*  static **util::PrefixedOutStream** **Fatal**\
 *Prints fatal messages prefixed with \[FATAL\], then terminates the program.*  static **util::PrefixedOutStream** **Info**\
 *Prints informational messages if --verbose is specified, prefixed with \[INFO \].*  static **util::PrefixedOutStream** **Warn**\
 *Prints warning messages prefixed with \[WARN \].*

## Detailed Description

Provides a convenient way to give formatted output.

The **Log** class has four members which can be used in the same way ostreams can be used:

- •

  **Log::Debug**

- •

  **Log::Info**

- •

  **Log::Warn**

- •

  **Log::Fatal**

Each of these will prefix a tag to the output (for easy filtering), and the fatal output will terminate the program when a newline is encountered. An example is given below.

```
Log::Info << "Checking a condition." << std::endl;
if (!someCondition())
  Log::Warn << "someCondition() is not satisfied!" << std::endl;
Log::Info << "Checking an important condition." << std::endl;
if (!someImportantCondition())
{
  Log::Fatal << "someImportantCondition() is not satisfied! Terminating.";
  Log::Fatal << std::endl;
}
```

Any messages sent to **Log::Debug** will not be shown when compiling in non-debug mode. Messages to **Log::Info** will only be shown when the --verbose flag is given to the program (or rather, the **CLI** class).

**See also:**

PrefixedOutStream, NullOutStream, **CLI**

Definition at line 65 of file log.hpp.

## Member Function Documentation

### static void mlpack::Log::Assert (boolcondition, const std::string &message = `'Assert Failed.'`)` [static]`

Checks if the specified condition is true. If not, halts program execution and prints a custom error message. Does nothing in non-debug mode.

Referenced by mlpack::emst::EdgePair::EdgePair().

## Member Data Documentation

### std::ostream& mlpack::Log::cout` [static]`

Reference to cout, if necessary.

Definition at line 98 of file log.hpp.

### util::NullOutStream mlpack::Log::Debug` [static]`

Dumps debug output into the bit nether regions.

Definition at line 84 of file log.hpp.

Referenced by mlpack::gmm::PositiveDefiniteConstraint::ApplyConstraint(), mlpack::gmm::GMM\< FittingType \>::GMM(), and mlpack::distribution::DiscreteDistribution::Probability().

### util::PrefixedOutStream mlpack::Log::Fatal` [static]`

Prints fatal messages prefixed with \[FATAL\], then terminates the program.

Definition at line 95 of file log.hpp.

Referenced by mlpack::kernel::SphericalKernel::ConvolutionIntegral(), and mlpack::gmm::EigenvalueRatioConstraint::EigenvalueRatioConstraint().

### util::PrefixedOutStream mlpack::Log::Info` [static]`

Prints informational messages if --verbose is specified, prefixed with \[INFO \].

Definition at line 89 of file log.hpp.

### util::PrefixedOutStream mlpack::Log::Warn` [static]`

Prints warning messages prefixed with \[WARN \].

Definition at line 92 of file log.hpp.

Referenced by mlpack::gmm::EigenvalueRatioConstraint::EigenvalueRatioConstraint(), mlpack::amf::RandomAcolInitialization\< p \>::Initialize(), and mlpack::cf::CF\< FactorizerType \>::NumUsersForSimilarity().

## Author

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