# Changes

## Hyperbolic paraboloid

, 13:14, 12 August 2011
Implicit and parametric descriptions
| Up to rigid motions (rotations, translations, reflections) || $z = \frac{y^2}{b^2} - \frac{x^2}{a^2}$ || || || ||
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| Up to similarity transformations || $\frac{y^2}{q^2} - x^2 = z$ || Here $q = b/a$ and we've done a similarity transformation. || || ||
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| Up to all affine transformations (''not permissible if we want to study geometric structure'') || $y^2 - x^2 = z$ || || || ||
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