fbm.h File Reference

Fractional Brownian motion (fBm) stimulus with Hurst exponent. More...

#include "coords.h"
#include "oakfield/operator_split.h"
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

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Classes
struct	SimStimulusFbmConfig
	Configuration for seeded fractional Brownian motion stimulus noise. More...

Typedefs
typedef struct SimStimulusFbmConfig	SimStimulusFbmConfig
	Configuration for seeded fractional Brownian motion stimulus noise.

Functions
SimResult	sim_add_stimulus_fbm_operator (struct SimContext *context, const SimStimulusFbmConfig *config, size_t *out_index)
	Register a fractional Brownian motion stimulus operator.
SimResult	sim_stimulus_fbm_config (struct SimContext *context, size_t operator_index, SimStimulusFbmConfig *out_config)
	Copy the current fBm configuration from a registered operator.
SimResult	sim_stimulus_fbm_update (struct SimContext *context, size_t operator_index, const SimStimulusFbmConfig *config)
	Replace or renormalize a registered fBm stimulus configuration.

Detailed Description

Fractional Brownian motion (fBm) stimulus with Hurst exponent.

Synthesizes fractal noise fields using a multi-octave cosine basis: f(x) = sum_o A 2^{-H o} cos(2π λ^o x + φ_o).

For complex fields, the sum is written as a complex-valued field with sinusoidal basis per octave.

Function Documentation

sim_add_stimulus_fbm_operator()

SimResult sim_add_stimulus_fbm_operator	(	struct SimContext *	context,
		const SimStimulusFbmConfig *	config,
		size_t *	out_index
	)

Register a fractional Brownian motion stimulus operator.

The implementation copies and normalizes config, initializes octave phases from the configured seed, and registers the noise operator on the target field.

Parameters

	context	Simulation context that will own the operator.
	config	Optional fBm configuration; NULL selects normalized defaults.
[out]	out_index	Optional destination for the registered operator index.

Returns

SIM_RESULT_OK on success, or an error code from validation, allocation, octave setup, or split-operator registration.

sim_stimulus_fbm_config()

SimResult sim_stimulus_fbm_config	(	struct SimContext *	context,
		size_t	operator_index,
		SimStimulusFbmConfig *	out_config
	)

Copy the current fBm configuration from a registered operator.

Parameters

	context	Simulation context containing the operator.
	operator_index	Index returned by sim_add_stimulus_fbm_operator().
[out]	out_config	Receives the operator's normalized configuration.

Returns

SIM_RESULT_OK on success, SIM_RESULT_INVALID_ARGUMENT for NULL pointers, SIM_RESULT_NOT_FOUND for a missing operator, or SIM_RESULT_INVALID_STATE when the operator has no stimulus state.

sim_stimulus_fbm_update()

SimResult sim_stimulus_fbm_update	(	struct SimContext *	context,
		size_t	operator_index,
		const SimStimulusFbmConfig *	config
	)

Replace or renormalize a registered fBm stimulus configuration.

Passing NULL for config keeps the existing configuration and reapplies normalization. A successful update refreshes octave data and invalidates the scheduler plan.

Parameters

context	Simulation context containing the operator.
operator_index	Index of the fBm operator to update.
config	Optional replacement configuration.

Returns

SIM_RESULT_OK on success, or an error code if lookup, octave setup, or state validation fails.