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pub use std::f64::consts::PI;

#[cfg(feature = "use_meter")]
mod unit {
    pub const METER: f64 = 1.0;
}
#[cfg(not(feature = "use_meter"))]
mod unit {
    pub const METER: f64 = 1000.0;
}
pub use unit::*;

pub const MILLIMETER: f64 = METER / 1000.0;

pub const ULTRASOUND_FREQUENCY: f64 = 40e3;

pub type Complex = nalgebra::Complex<f64>;

pub const ABSOLUTE_THRESHOLD_OF_HEARING: f64 = 20e-6;

pub const T4010A1_AMPLITUDE: f64 = 275.574246625 * 200.0 * MILLIMETER; // [Pa*mm]