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use format::packed::Variant;
use format::Packed;
use operation::Transpose;
use Element;

impl<T: Element> Transpose for Packed<T> {
    fn transpose(&self) -> Self {
        let &Packed { size, variant, .. } = self;
        let lower = variant == Variant::Lower;
        let mut matrix = Packed::new(size, variant.flip());
        let mut k = 0;
        for j in 0..size {
            for i in j..size {
                if lower {
                    matrix.values[arithmetic!(i, 1, i) + j] = self.values[k];
                } else {
                    matrix.values[k] = self.values[arithmetic!(i, 1, i) + j];
                }
                k += 1;
            }
        }
        matrix
    }
}

#[cfg(test)]
mod tests {
    use format::packed::Variant;
    use prelude::*;

    #[test]
    fn transpose_lower() {
        let matrix = new!(
            4,
            Variant::Lower,
            vec![1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0]
        );
        let matrix = matrix.transpose();
        assert_eq!(
            matrix,
            new!(
                4,
                Variant::Upper,
                vec![1.0, 2.0, 5.0, 3.0, 6.0, 8.0, 4.0, 7.0, 9.0, 10.0]
            )
        );
    }

    #[test]
    fn transpose_upper() {
        let matrix = new!(
            4,
            Variant::Upper,
            vec![1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0]
        );
        let matrix = matrix.transpose();
        assert_eq!(
            matrix,
            new!(
                4,
                Variant::Lower,
                vec![1.0, 2.0, 4.0, 7.0, 3.0, 5.0, 8.0, 6.0, 9.0, 10.0]
            )
        );
    }
}