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Diff — Cartesian coordinate system

Revision #1060 → #1758 · back to history

modifiedOblique coordinate system11557c2ca201
FieldFrom #1060To #1758
mathlib.declBasisModule.Basis
noteA general (non-orthonormal) Basis provides oblique coordinates, but oblique systems are not separately named.A general (non-orthonormal) Module.Basis provides oblique coordinates, but oblique systems are not separately named.
addedPythagorean theorem (Cartesian form)73e800046545
modifiedRotation about the origindced95c49030
FieldFrom #1060To #1758
noteOrientation.rotation is rotation by an oriented angle in an oriented 2D inner product space, matching the cos/sin formula (cf. Complex.toMatrix_rotation).Orientation.rotation is rotation by an oriented angle in an oriented 2D inner product space, matching the cos/sin formula.
modifiedReflection across coordinate axesc112ac11f1b5
FieldFrom #1060To #1758
mathlib.declreflectionSubmodule.reflection
noteReflection in a subspace specializes to axis reflections, but the coordinate formula (x,y)↦(-x,y) is not a stated lemma.Submodule.reflection in a hyperplane specializes to axis reflections, but the coordinate formula (x,y)↦(-x,y) is not a stated lemma.
addedReflection across line through origin at angle2cad101a5604
modifiedAffine transformations via matricesb6d6fb5f73cd
FieldFrom #1060To #1758
anchors[{"section":"General matrix form of the transformations","snippet":"All affine transformations of the plane can be described in a uniform way by using matrices."},{"type":"math_alttext","value":"{\\displaystyle {\\begin{pmatrix}x'\\\\y'\\end{pmatrix}}=A{\\begin{pmatrix}x\\\\y\\end{pmatrix}}+b,}"},{"type":"math_alttext","value":"{\\displaystyle A={\\begin{pmatrix}A_{1,1}&A_{1,2}\\\\A_{2,1}&A_{2,2}\\end{pmatrix}}}"},{"type":"math_alttext","value":"{\\displaystyle {\\begin{aligned}x'&=xA_{1,1}+yA_{1,1}+b_{1}\\\\y'&=xA_{2,1}+yA_{2,2}+b_{2}.\\end{aligned}}}"}][{"section":"General matrix form of the transformations","snippet":"All affine transformations of the plane can be described in a uniform way by using matrices."},{"type":"math_alttext","value":"{\\displaystyle {\\begin{pmatrix}x'\\\\y'\\end{pmatrix}}=A{\\begin{pmatrix}x\\\\y\\end{pmatrix}}+b,}"},{"type":"math_alttext","value":"{\\displaystyle A={\\begin{pmatrix}A_{1,1}&A_{1,2}\\\\A_{2,1}&A_{2,2}\\end{pmatrix}}}"},{"type":"math_alttext","value":"{\\displaystyle {\\begin{aligned}x'&=xA_{1,1}+yA_{1,1}+b_{1}\\\\y'&=xA_{2,1}+yA_{2,2}+b_{2}.\\end{aligned}}}"}]
modifiedRotation iff A is rotation matrix1b995507cb78
FieldFrom #1060To #1758
noteSO(n) is formalized as specialOrthogonalGroup (with a 2×2 characterization), but the geometric iff for rotations about a point is not stated.SO(n) is formalized as specialOrthogonalGroup, but the geometric iff for rotations about a point is not stated.
modifiedComposition by multiplying matrices191908516801
FieldFrom #1060To #1758
anchors[{"section":"General matrix form of the transformations","snippet":"transformations can be composed by simply multiplying the associated transformation matrices"},{"type":"math_alttext","value":"{\\displaystyle {\\begin{pmatrix}x'\\\\y'\\\\1\\end{pmatrix}}=A'{\\begin{pmatrix}x\\\\y\\\\1\\end{pmatrix}},}"},{"type":"math_alttext","value":"{\\displaystyle A'={\\begin{pmatrix}A_{1,1}&A_{1,2}&b_{1}\\\\A_{2,1}&A_{2,2}&b_{2}\\\\0&0&1\\end{pmatrix}}.}"}][{"section":"General matrix form of the transformations","snippet":"transformations can be composed by simply multiplying the associated transformation matrices"},{"type":"math_alttext","value":"{\\displaystyle {\\begin{pmatrix}x'\\\\y'\\\\1\\end{pmatrix}}=A'{\\begin{pmatrix}x\\\\y\\\\1\\end{pmatrix}},}"},{"type":"math_alttext","value":"{\\displaystyle A'={\\begin{pmatrix}A_{1,1}&A_{1,2}&b_{1}\\\\A_{2,1}&A_{2,2}&b_{2}\\\\0&0&1\\end{pmatrix}}.}"}]
modifiedAffine transformations of the plane5dba9bcbe4d7
FieldFrom #1060To #1758
anchors[{"section":"Affine transformation","snippet":"Affine transformations of the Euclidean plane are transformations that map lines to lines"},{"type":"math_alttext","value":"{\\displaystyle {\\begin{pmatrix}A_{1,1}&A_{2,1}&b_{1}\\\\A_{1,2}&A_{2,2}&b_{2}\\\\0&0&1\\end{pmatrix}}{\\begin{pmatrix}x\\\\y\\\\1\\end{pmatrix}}={\\begin{pmatrix}x'\\\\y'\\\\1\\end{pmatrix}}.}"}][{"section":"Affine transformation","snippet":"Affine transformations of the Euclidean plane are transformations that map lines to lines"},{"type":"math_alttext","value":"{\\displaystyle {\\begin{pmatrix}A_{1,1}&A_{2,1}&b_{1}\\\\A_{1,2}&A_{2,2}&b_{2}\\\\0&0&1\\end{pmatrix}}{\\begin{pmatrix}x\\\\y\\\\1\\end{pmatrix}}={\\begin{pmatrix}x'\\\\y'\\\\1\\end{pmatrix}}.}"}]
modifiedStandard right-handed orientationd36480292bdb
FieldFrom #1060To #1758
mathlib.declpositiveOrientationModule.Oriented.positiveOrientation
notepositiveOrientation is the standard/positive orientation determined by the standard basis.Module.Oriented.positiveOrientation is the standard/positive orientation determined by the standard basis.
modifiedIdentification with complex numbersdd34fe418f62
FieldFrom #1060To #1758
noteComplex.equivRealProd is the equivalence ℂ ≃ ℝ × ℝ identifying z = x + iy with (x, y) (with linear/CLM versions equivRealProdLm/equivRealProdCLM).Complex.equivRealProd is the equivalence ℂ ≃ ℝ × ℝ identifying z = x + iy with (x, y).
addedIdentification with quaternions (3D)0ae5b95cf780