2016년 3월 29일 화요일

Variance and Standard Deviation



Before you see this post,

see

Possibility and Mean










If we find variance like upper picture,
variance has no meaning.




So, variance is calculated like bottom picture.
Standard deviation is a positive square root of variance. 






Possibility and Mean









Example






Differential of A Function : sin x, cos x





Before you see this post,

see

A Property of Limit of A Function : f(x)/g(x)


















Synthesis of Trigonometric Functions




Before you see this post,

see

Distance between A Point and A line


and














Distance between A Point and A line





Before you see this post,

see

A Property of Perpendicular Lines










correction in picture : parpendicular -> perpendicular







A Property of Perpendicular Lines







Relationship between Integral and Differential





Before you see this post,

see

Riemann Sum and Riemann Integral


and








f(q) can be integrated by Riemann integral and is a continuous function

and

F(x) can be differentiated.





Integral is an inverse operation of Differential.




2016년 3월 28일 월요일

Error Estimate of Riemann Sum



Before you see this post,

see

Riemann Sum and Riemann Integral





f(x) can be integrated by Riemann integral.





If you want to know more,







Complex Number







Magnitude of a complex number z

 \sqrt { z \bar{z}} = \sqrt { a^2 + b^2 }


\bar{z} = a-bi

\bar{z} is a complex conjugate of z.







Real Number





National Number ⊂ Integer ⊂ Rational Number ⊂ Real Number

Irrational Number ⊂ Real Number



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