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Computer Graphics

Common sets of interest include

• R—the real numbers;
• R+—the nonnegative real numbers (includes zero);
• R2—the ordered pairs in the real 2D plane;
• Rn—the points in n-dimensional Cartesian space;
• Z—the integers;
• S2—the set of 3D points (points in R3) on the unit sphere.

Logarithms

The “log base a” of x is written l o g a x log_a{x} logax and is defined as “the exponent to which a must be raised to get x.”
Note that the logarithm base a and the function that raises a to a power are inverses of each other.
y = log ⁡ a x ⇔ a y = x y = \log_a{x} ⇔ a^y = x y=logaxay=x
a log ⁡ a ( x ) = x a^{\log_a{(x)}} = x aloga(x)=x
log ⁡ a ( a x ) = x \log_a({a^x}) = x loga(ax)=x
log ⁡ a ( x y ) = log ⁡ a x + log ⁡ a y \log_a{(xy)} = \log_a{x} + \log_a{y} loga(xy)=logax+logay
log ⁡ a ( x / y ) = log ⁡ a x − log ⁡ a y \log_a{(x/y)} = \log_a{x} - \log_a{y} loga(x/y)=logaxlogay
log ⁡ a x = log ⁡ a b ∗ log ⁡ a x \log_a{x} = \log_a{b} * \log_a{x} logax=logablogax

The logarithm with base e is called the natural logarithm.
ln ⁡ x ≡ log ⁡ e y \ln{x} \equiv \log_e{y} lnxlogey

Solving Quadratic Equations

A quadratic equation has the form:$ Ax^2+Bx+C=0 $
x = − B ± B 2 − 4 A C 2 A x = \frac{-B\pm \sqrt{B^2 - 4AC}}{2A} x=2AB±B24AC
D ≡ B 2 − 4 A C D \equiv B^2 - 4AC DB24AC

Trigonometry

d e g r e e s = 180 π r a d i a n s degrees = \frac{180}{\pi}radians degrees=π180radians
r a d i a n s = π 180 d e g r e e s radians = \frac{\pi}{180}degrees radians=180πdegrees

Shifting identities:

sin ⁡ ( − A ) = − sin ⁡ ( A ) \sin(-A) = -\sin(A) sin(A)=sin(A)
cos ⁡ ( − A ) = cos ⁡ ( A ) \cos(-A) = \cos(A) cos(A)=cos(A)
tan ⁡ ( − A ) = − tan ⁡ ( A ) \tan(-A) = -\tan(A) tan(A)=tan(A)
sin ⁡ ( π 2 − A ) = cos ⁡ ( A ) \sin(\frac{\pi}{2}-A) = \cos(A) sin(2πA)=cos(A)
cos ⁡ ( π 2 − A ) = sin ⁡ ( A ) \cos(\frac{\pi}{2}-A) = \sin(A) cos(2πA)=sin(A)
tan ⁡ ( π 2 − A ) = cot ⁡ ( A ) \tan(\frac{\pi}{2}-A) = \cot(A) tan(2πA)=cot(A)

Pythagorean identities:

sin ⁡ 2 A + cos ⁡ 2 A = 1 \sin^2A + \cos^2A=1 sin2A+cos2A=1
sec ⁡ 2 A − tan ⁡ 2 A = 1 ( s e c = c o s − 1 ) \sec^2A - \tan^2A=1 (sec = cos^{-1}) sec2Atan2A=1(sec=cos1)
csc ⁡ 2 A − cot ⁡ 2 A = 1 ( c s c = s i n − 1 ) \csc^2A - \cot^2A=1 (csc= sin^{-1}) csc2Acot2A=1(csc=sin1)

Addition and subtraction identities:

sin ⁡ ( A + B ) = sin ⁡ A cos ⁡ B + sin ⁡ B cos ⁡ A \sin(A+B) = \sin{A}\cos{B}+\sin{B}\cos{A} sin(A+B)=sinAcosB+sinBcosA
sin ⁡ ( A − B ) = sin ⁡ A cos ⁡ B − sin ⁡ B cos ⁡ A \sin(A-B) = \sin{A}\cos{B}-\sin{B}\cos{A} sin(AB)=sinAcosBsinBcosA
sin ⁡ ( 2 A ) = 2 sin ⁡ A cos ⁡ B \sin(2A) = 2\sin{A}\cos{B} sin(2A)=2sinAcosB

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