terrustrial 0.1.1

A Rust library for geospatial statistics, variograms, and kriging.
Documentation 
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use super::IsoVariogramModel;

#[derive(Debug, Clone, Default, Copy)]
pub struct IsoSpherical {
    pub range: f64,
    pub sill: f64,
}

impl IsoSpherical {
    pub fn new(range: f64, sill: f64) -> Self {
        Self { range, sill }
    }

    pub fn variogram(&self, h: f64) -> f64 {
        if h < self.range {
            return self.sill * (1.5 * h / self.range - 0.5 * (h / self.range).powi(3));
        }
        self.sill
    }

    pub fn covariogram(&self, h: f64) -> f64 {
        self.sill - self.variogram(h)
    }

    //derivative of variogram with respect to range
    pub fn variogram_dr(&self, h: f64) -> f64 {
        let r = self.range;

        self.sill * (1.5 * h * h * h / (r * r * r * r) - 1.5 * h / (r * r))
    }

    // derivative of variogram with respect to sill
    pub fn variogram_ds(&self, h: f32) -> f32 {
        let r = self.range as f32;
        if h <= r {
            return 1.5 * h / r - 0.5 * (h / r).powi(3);
        }

        0.0
    }

    pub fn parameter_names() -> Vec<&'static str> {
        vec!["range"]
    }

    pub fn param_cnt() -> usize {
        2
    }

    pub fn update_from_slice(&mut self, params: &[f64]) {
        self.range = params[0];
        self.sill = params[1];
    }
}

impl IsoVariogramModel for IsoSpherical {
    fn c_0(&self) -> f64 {
        self.sill
    }

    fn variogram(&self, h: f64) -> f64 {
        if h < self.range {
            return self.sill * (1.5 * h / self.range - 0.5 * (h / self.range).powi(3));
        }
        self.sill
    }

    fn covariogram(&self, h: f64) -> f64 {
        self.sill - self.variogram(h)
    }
}