Ode

Auto-generated from src/stdlib/ode.mcrs — do not edit manually.

API

• ode_mul_fx
• ode_weighted_increment
• ode_reset
• ode_get_system
• ode_get_t
• ode_get_y
• ode_get_y2
• ode_get_k
• ode_get_extra
• ode_get_steps
• ode_step
• ode_run
• ode_run2

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ode_mul_fx v2.0.0

Fixed-point multiplication: a_fx * b_fx / 10000.

fn ode_mul_fx(a_fx: int, b_fx: int): int

Parameters

Parameter	Description
a_fx	First operand ×10000
b_fx	Second operand ×10000

Returns: Product in ×10000 scale

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ode_weighted_increment v2.0.0

Compute the RK4 weighted increment: h * (k1 + 2k2 + 2k3 + k4) / 6.

All values are ×10000. The divisor 60000 = 6 × 10000.

fn ode_weighted_increment(h_fx: int, deriv_sum_fx: int): int

Parameters

Parameter	Description
h_fx	Step size ×10000
deriv_sum_fx	k1 + 2k2 + 2k3 + k4 in ×10000

Returns: Weighted increment in ×10000

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ode_reset v2.0.0

Initialise the ODE module state in storage rs:ode.

fn ode_reset(system_id: int, t_fx: int, y_fx: int, y2_fx: int, k_fx: int, extra_fx: int)

Parameters

Parameter	Description
system_id	Built-in system constant (1=decay, 2=growth, 3=oscillator)
t_fx	Initial time ×10000
y_fx	Initial primary variable y(0) ×10000
y2_fx	Initial secondary variable y'(0) ×10000 (for system 3)
k_fx	Rate/spring constant ×10000
extra_fx	Damping coefficient ×10000 (for system 3)

Example

ode_reset(1, 0, 10000, 0, 10000, 0)

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ode_get_system v2.0.0

Return the current system ID from ODE state.

fn ode_get_system(): int

Returns: System ID stored in slot 0

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ode_get_t v2.0.0

Return the current time t from ODE state (×10000).

fn ode_get_t(): int

Returns: Current time ×10000

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ode_get_y v2.0.0

Return the current primary variable y from ODE state (×10000).

fn ode_get_y(): int

Returns: Current y value ×10000

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ode_get_y2 v2.0.0

Return the current secondary variable y' from ODE state (×10000).

fn ode_get_y2(): int

Returns: Current y' value ×10000 (meaningful for system 3 only)

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ode_get_k v2.0.0

Return the rate constant k from ODE state (×10000).

fn ode_get_k(): int

Returns: Rate constant ×10000

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ode_get_extra v2.0.0

Return the extra parameter from ODE state (×10000).

fn ode_get_extra(): int

Returns: Extra parameter ×10000 (damping for system 3)

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ode_get_steps v2.0.0

Return the number of steps taken so far.

fn ode_get_steps(): int

Returns: Step count (plain integer)

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ode_step v2.0.0

Advance the ODE state by one RK4 step of size h_fx.

Updates time t, primary variable y (and y2 for system 3), and increments the step counter in storage rs:ode.

fn ode_step(h_fx: int)

Parameters

Parameter	Description
h_fx	Step size ×10000 (e.g. 1000 = 0.1 time unit)

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ode_run v2.0.0

Run steps RK4 steps of a scalar ODE system and store results in module state.

Built-in systems: 1 = exponential decay (dy/dt = -k·y), 2 = exponential growth (dy/dt = k·y).

fn ode_run(system_id: int, t0_fx: int, y0_fx: int, h_fx: int, steps: int, k_fx: int)

Parameters

Parameter	Description
system_id	Built-in system constant (1 or 2 for scalar systems)
t0_fx	Initial time ×10000
y0_fx	Initial y value ×10000
h_fx	Step size ×10000
steps	Number of RK4 steps to execute
k_fx	Rate constant ×10000

Example

ode_run(1, 0, 10000, 1000, 10, 10000)
let y: int = ode_get_y()

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ode_run2 v2.0.0

Run steps RK4 steps of a 2D ODE system (e.g. harmonic oscillator).

Built-in system 3: y' = y2, y2' = -k·y - extra·y2.

fn ode_run2(system_id: int, t0_fx: int, y0_fx: int, y20_fx: int, h_fx: int, steps: int, k_fx: int, extra_fx: int)

Parameters

Parameter	Description
system_id	Built-in system constant (use 3 for harmonic oscillator)
t0_fx	Initial time ×10000
y0_fx	Initial y value ×10000
y20_fx	Initial y' value ×10000
h_fx	Step size ×10000
steps	Number of RK4 steps to execute
k_fx	Spring constant ×10000
extra_fx	Damping coefficient ×10000

Example

ode_run2(3, 0, 10000, 0, 1000, 20, 10000, 500)

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