Contents

Fortran API Interface

Warning

This source code documentation was generated by AI and may contain errors or inaccuracies. Users should verify information against the actual source code and consult the official SPEX user manual for authoritative usage instructions.

Introduction

The SPEX Fortran interface provides comprehensive access to all X-ray spectral analysis capabilities through a modern, object-oriented Fortran API. This interface serves as the foundation for both the interactive SPEX command prompt and the Python interface, offering direct programmatic control over all SPEX functionality.

Architecture Overview

The SPEX Fortran interface is built using a layered architecture that separates concerns and provides multiple access levels:

Application Layer

  • spex.f90: Main interactive program

  • Utility programs: stepcontour, trafo, linid, etc.

Interface Layer

  • spexapi.f90: Unified Fortran API (facade pattern)

  • spex_command.f90: Interactive command interface

Core Library Layer

  • spexio: Data input/output and spectrum management

  • spexmodel: Spectral modeling and atomic physics

  • spexfit: Parameter estimation and statistical analysis

  • spexplot: Plotting and visualization

Utility Layer

  • spexutils: Common utilities and helper functions

  • spexmath: Mathematical operations and algorithms

Target Audiences

End Users

Use the interactive command prompt (spex) for X-ray spectral analysis. The command interface provides intuitive access to all SPEX capabilities through text commands.

Python Developers

Access SPEX functionality through the Python interface, which wraps the Fortran API to provide Pythonic access to spectral analysis tools.

Fortran Developers

Use the spexapi.f90 module directly for custom applications, batch processing, or integration with other Fortran codes.

SPEX Contributors

Extend SPEX by adding new models, fitting algorithms, or analysis tools using the modular library architecture.

Getting Started

For Interactive Use:

$ spex
SPEX4> data mydata.res mydata.spo
SPEX4> comp pow
SPEX4> fit
SPEX4> plot

For Fortran Development:

program my_analysis
    use spex_api
    implicit none

    type(sapi) :: spex
    integer    :: ier

    ! Initialize SPEX
    call spex%init()

    ! Load data
    call spex%data('mydata.res', 'mydata.spo', ier)

    ! Add model component
    call spex%comp('pow', 1, 1, ier)

    ! Perform fit
    call spex%fit(ier)

    ! Clean up
    call spex%final()
end program

For Python Development:

import pyspex

# Initialize session
s = pyspex.Spex()

# Load data and fit model
s.data('mydata.res', 'mydata.spo')
s.comp('pow')
s.fit()

# Access results
chi2 = s.fit_statistic()

Development Guidelines

Adding New Functionality

  1. Implement core functionality in appropriate library (spexio, spexmodel, etc.)

  2. Add API method to spexapi.f90 for programmatic access

  3. Add command handler to spex_command.f90 for interactive use

  4. Update Python bindings if needed

Error Handling

All Fortran API methods use consistent error reporting through integer status codes:

  • ier = 0: Success

  • ier > 0: Warning or non-fatal error

  • ier < 0: Fatal error requiring intervention

Memory Management

SPEX uses automatic memory management through Fortran derived types with proper initialization and finalization procedures.

Performance Considerations

  • Core computational routines are optimized for large datasets

  • Memory allocation is minimized during fitting iterations

  • Parallel processing support where applicable

Module Documentation

The following sections provide detailed documentation for each component of the SPEX Fortran interface:

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