diff --git a/Courses/EE1M2_Calculus_and_Linear_Algebra.typ b/Courses/EE1M2_Calculus_and_Linear_Algebra.typ new file mode 100644 index 0000000..63562b0 --- /dev/null +++ b/Courses/EE1M2_Calculus_and_Linear_Algebra.typ @@ -0,0 +1,137 @@ +#import "../template/lib.typ" : * +#set page(paper: "a4") + +#show: notes.with( + title: [EE1M2], + subtitle: [Calculus and Linear Algebra], + author: "Folkert Kevelam" +) + += Lecture 1 - Parametric surfaces + +== Parametric surfaces + +There are multiple ways to parametrize a surface. Given the paraboloid $z = x^2 + y^2$, +it can be paramaterized by the functions: $r(x,y,z) = chevron.l x,y,x^2 + y^2 chevron.r$ or +$r(theta, z) = chevron.l sqrt(z)cos(theta),sqrt(z)sin(theta),z chevron.r$. + +#definition[ + A *parametric surface* $S$ in $RR^3$ is a 2-dimensional set of points whose + positions are given by the continuous function: + + $ + r(u,v) = chevron.l x(u,v), y(u,v), z(u,v) chevron.r "with" (u,v) in D + $ + + where $D$ is a region in the uv-plane. Here $u$ and $v$ are called *parameters* + and $r(u,v)$ is called the parameterization of $S$. +] + +There are special curves that correspond to constant values of $u$ and $v$, and +are referred to as *grid curves*. + +#theorem[ + Let $S$ be the graph of a function $f$ of two variables, $x$ and $y$, with + domain $D$. Then, $S$ can be parameterized by + + $ + r(x,y) = chevron.l x, y, f(x,y) chevron.r + $ + + with $(x,y)$ in $D$. +] + +#remark[ + Not each surface in $RR^3$ is the graph of a function. Example: a sphere +] + +#example[ + Parameterization of a half-sphere: + + $ + r(x,y) &= chevron.l x, y, sqrt(1-x^2-y^2) chevron.r "with" x^2 + y^2 + z^2 <= 1 \ + r(theta,r) &= chevron.l r cos(theta), r sin(theta), sqrt(1-r^2) chevron.r "with" 0 <= r <= 1, 0<=theta<= 2 pi\ + r(theta,phi,rho) &= chevron.l rho cos(theta) sin(phi), rho sin(theta) sin(phi), rho cos(phi) chevron.r "with" 0 <= rho <= 1, 0 <= phi <= pi/2, 0 <= theta <= 2 pi + $ +] + +#definition[ + A surface in $RR^3$ is called a *closed surface*, if it is the boundary + of a solid region in $RR^3$. +] + +#example[ + Parameterization of a shifted half-sphere: + + $ + x^2 + y^2 + (z-a)^2 <= rho^2 \ + x^2 + y^2 + z^2 - 2 a z + a^2 <= rho^2 \ + (x^2 + y^2 + z^2) - 2 a z + a^2 <= rho^2 + $ +] + +#definition[ + A surface $S$ in $RR^3$ that is generated by rotating a curve about an + axis, is called a *surface of revolution* +] + +#theorem[ + Let $S$ be the surface obtained by rotating a parametric curve $C$, with + $r_c(t) = chevron.l x(t), y(t), o chevron.r$ and $a <= t <= b$, about the + x-axis. Then, $S$ can be parameterized by + + $ + r_S(t,theta) = chevron.l x(t), y(t) cos(theta), y(t) sin(theta) chevron.r + $ + + with $a<= t <= b$ and $0 <= theta <= 2 pi$ +] + +== Tangent vectors and normal vectors + +#proposition[ + Consider the vector function $r(u,v) = chevron.l x(u,v), y(u,v), z(u,v) chevron.r$ +] + +#remark[ + Consider the surface $S$ parameterized by a vector function $r(u,v)$. The + vectors $r_u (u_0, v_0)$ and $r_v (u_0, v_0)$ are tangent to the grid curves + $r(u, v_0)$ and $r(u_0, v)$ respectively. +] + +#corollary[ + The vectors $r_u (u_0, v_0)$ and $r_v (u_0, v_0)$ ar +] + +#definition[ + Let $P$ be a point in a surface $S$ that is not on the boundary of $S$. Then + $S$ is called *smooth* at $P$ if $r_u "cross" r_v eq.not 0$ +] + +#definition[ + A nonzero vector $n$ that is perpendicular to the tangent plane of $S$ at $P$ + is called a *normal vector* of $S$ at $P$. +] + +#theorem[ + Suppose a parametric surface $S$, given by $r(u,v)$, is smooth ath the point + $r(u_0, v_0)$. Then the vector $n=r_u (u_0, v_0) times r_v (u_0, v_0)$ is a normal + vector of $S$ at $r(u_0, v_0)$ +] + +== Areas of parametric surfaces + +#theorem[ + Suppose $S$ is a smooth surface given by + + $ + r(u,v) = chevron.l x(u,v), y(u,v), z(u,v) chevron.r, (u,v) in D + $ + + where $S$ is covered once as $(u,v)$ ranges through parameter domain $D$. + The *surface area* of $S$ is + + $ + "area"(S) = integral.double_S d S = attach(limits(integral.double),b:D) |r_u times r_v| d u d v + $ +]