레이블이 analysis인 게시물을 표시합니다. 모든 게시물 표시
레이블이 analysis인 게시물을 표시합니다. 모든 게시물 표시

2016년 5월 24일 화요일

Express Functions from Taylor Series





Before read this post,

read

Taylor Series





Taylor Series and Maclaurin Series



We can express some functions by the series.







Fourier Transform from Fourier Series





Before you see this post,

see


Definite Integral of Multiplied 2 Trigonometric Functions



Express Functions from Taylor Series









We can think f(t) is sum of wave functions and a constant.

if t=0, f(0) = a_0.




Then, let's find a_0.


We can find a_0 like process above.






Through

Definite Integral of Multiplied 2 Trigonometric Functions,


we can find a_n ( except n = 0 ) and b_n.







Use

Express Functions from Taylor Series,


we can develop the formula.




In the process, we can derive Fourier Transform from Fourier Series.



2016년 3월 28일 월요일

Riemann Sum and Riemann Integral







If the limit of Riemann sum is convergence,
f(x) can be integrated by Riemann integral.




If f(x) can be integrated by Riemann integral,
some properties in picture below are valid.




If you want to know error of Riemann Sum

see

Error Estimate of Riemann Sum









2016년 3월 3일 목요일

Green's Theorem

1. Setting


[pic 1]

Let a closed curve C be set on x,y plane.
Domain D is covered by closed curve C.

[pic 2]

Let's functions, M(x,y) and N(x,y) exist and they have partial derivatives on D.
The formula can be notated like it in [pic 2] on C.

[pic 3]

This formula can be divided like [pic 3] 
because M(x,y)dx and N(x,y)dy are on same closed curve C. 




2. Induction

2-1. Considering The Formula at X Coordinate

First, we consider the formula in [pic 2] at x coordinate.

[pic 4]

[pic 5]

We set a domain like a formula in [pic 5].

[pic 6]

So, result is like [pic 6] on x coordinate.



2-2. Considering The Formula at Y Coordinate

Next, we also consider the formula in [pic 2] at y coordinate.

[pic 7]

[pic 8]

We set a domain like a formula in [pic 8].

[pic 9]

So, result is like [pic 6] on y coordinate.





3. Conclusion

[pic 10]

We can combine same domain.
Therefore, we can prove Green's Theorem.