.
PDF garbled problem solution:Sudo apt-Get install xpdf-Chinese-SimplifiedIf not, perform the following steps:1. Download poppler-data and decompress it.2 In the terminal: CD/extract path/poppler-data-0.13, enter sudo make install datadir =/usr/share.After opening the PDF file again, Chinese characters are displayed normally.
3. After poppler is installed, if it cannot be properly displayed, run the following command:Sudo RM/etc/fonts/CONF. d/49-sansserif.conf
4. Activate the NVIDIA Graph
: ([1-9]). ([1-9])
(Select the wildcard Mode)
Enter \ 1-\ 2 in the replacement box.
Source: http://blog.sina.com.cn/s/blog_591e979d0100h0qt.html
2.Word search and replacement Tips 1
For example, Mr. a B
Mr. c d
To be replaced
Mr. a BMr. c d
Form,
How do I replace with wildcards?
-----------------Search: Mr. ([a-zA-Z] {1,} [a-zA-Z] {1 ,})Replace: \ 1, mr.
1. In the search, brackets can be used to define a variable. The replacement can be referenced in \ 1 and \ 2 in their order.2. [] indicates a
example, uint32 y;Uint32 x = y/7; // It is known that Y is a multiple of 7.Change to uint32 x = (uint32) (y * m); // where M = (5*(1
9. Approximate Calculation Division (this alternative method is not equivalent)Optimize the operation of divisor 255 (257 or 1026, and so on) (or, and the formula for pushing and exporting is slightly different)For example, in color processing: uint8 color = colorsum/255;Changed to: uint8 color = colorsum/256; that is, color = colorsum> 8;This error is often acce
the same, then A is a matrix, the data points of row I are, and B is a vector whose value is. It is also known that calculating the inverse of a matrix is quite time-consuming, and that there are numerical instability in the inversion (for example, it is almost impossible to reverse the Hilbert matrix). Thus, this method of calculation is sometimes not worth advocating.In contrast, although there are some drawbacks to the gradient descent method, the number of iterations may be relatively high,
force F, that is opposite, the deceleration motion, analogy to the speed of the derivative acceleration is negative.3. Hessian matrix:
In fact, the Hessian matrix is the Jacobian matrix of the gradient vector g (x) to the argument x:
In mathematics, the Haisen matrix (Hessian matrix or Hessian) is a square matrix of second-order partial derivatives of an independent variable as a real-valued function of a vector. The Haisen matrix is applied to the large-scale optimization problem solved by
mapped by G (z). 10 Newton method to solve maximum likelihood estimation
The methods of maximum likelihood estimation used in sections 7th and 9th are the methods of derivation iteration, and the Newton descent method is introduced, so that the results can be quickly convergent.
When the solution is required, if f is conductive, then the formula can be iterated
To iteratively solve the minimum value.
When
There are many ways to use the program to find the integral, this article is mainly about Newton-Cortez formula.The easiest thing for a classmate to learn about interpolation is to use an interpolation function instead of an integral function to find an integral, but in reality it doesn't work in most scenarios.The interpolation function is usually a polynomial of not more than n times, if the interpolation function to find the integral, it will intro
Taylor's unfolding, and the basic idea of these numerical methods, which can be said that there is no such a way to do so without such an expansion.In fact, many places in mathematics use this specific technique, such as the isomorphism of "group" to "permutation group" in discrete mathematics. Many of the problems in this course are to solve the problem of multi-fetching Lagrange expansion, and the higher order can get better fitting effect. This is a slippery question.# # SmoothHow to achieve
; that is, color = colorsum> 8;This error is often acceptable in color processing.To reduce the error, you can change it to uint8 color = (colorsum + (colorsum> 8)> 8;Derivation: x/255 = (x + x/255)/(255 + 1) = (x + A)> 8; A = x/255;Change a to a = x> 8 (A small error is introduced). Then, the formula x/255 equals (x + (x> 8)> 8 FormulasLikewise, x/255 is approximately equal to (x + (x> 8) + (x> 16)> 8 and other more accurate formulas (Please export the error items to determine whether the accur
The SQRT () function is a common function supported by most languages. It implements open-side operations. The open-side operations were first mentioned in chapter 9 arithmetic by Liu Hui, a mathematician in China's Wei and Jin Dynasties. Today, I wrote several functions and several God-class programs from other countries to help you understand the magic of SQRT.
1. Ancients algorithm (Violence Law)
Principle: from 0 to 0.00001, 000002... try one by one until the square root of X is found. The C
Directory
Quantlib financial computing-a tool for solving mathematical tools
Overview
Call Method
Non-Newton algorithm (derivative not required)
Newton algorithm (derivative required)
Unless otherwise specified, all the programs in this article are python3 code.
Quantlib financial computing-a tool for solving mathematical tools
Load Module
import QuantLib as qlimport scipy
be seen that the dichotomy is exactly the same as the system's method, but the performance is hundreds of times times worse. Why is there such a big difference? Is there any better way to do this? Don't.... Oh, by the way, remember the high number of lessons we had, once the teacher taught us "Newton iterative method to quickly find square root", or this method can help us, the specific steps are as follows:Find the approximate value of the square ro
squares in the graph. This section mainly discusses the polynomial interpolation method.the fundamental point of polynomial interpolation is to establish a special form of polynomial, called interpolation polynomial .To understand the meaning of interpolation polynomial in depth, let's look at some basic laws of the polynomial:First, the polynomial is a function with the following form:P (x) = a0 + a1x + a2x2 + ... + anxnThe A0,...,an here is the coefficient . when an is a nonzero integer, this
function f (x) and its gradient column vector as follows
function [F,df]=detaf (x);
F=x (1) ^2+25*x (2) ^2;
Df=[2*x (1)
50*x (2)];
% Write main program file zuisu.m as follows:
CLC
x=[2;2];
[F0,g]=detaf (x);
While Norm (g) >0.000001
p=-g/norm (g);
T=1.0;f=detaf (x+t*p);
While f>f0
T=T/2;
F=detaf (x+t*p);
End
X=x+t*p;
[F0,g]=detaf (x);
End
X,f0
∇ also need to be skilled in its use, to be continued ~
Newton method:. Starting from an initial point, eac
method that contains this polynomial is the Lagrange equation: where the base functions (cardinal function)li(x)">li(x)">li (x)As follows:
Example 1:n=1">n=1">n=1,p1(x)=y0l0(x)+y1l1(x)">p1(x)=y0l0(x)+y1l1(x)">p1 (x) =y0l0 (x) +y1l1 (x )
Example 2:n=2">n=2,
By observing, the base function has the following properties
is a polynomial of degrees of freedom n">n
Note: Kronecker Delta (#x03B4;ij">#x03B4;ij">Δij), whenn=2">n=2">n=2,x0=0,x1=2,x2=3">x0=0,x1=2,x2=3">x0=0,x1=2,x2=3When the
Root is a basic problem of numerical calculation, and it is usually solved by iterative algorithm, which includes fixed point iterative method, Newton-Pull enrichment Algorithm, secant method and dichotomy method.
Fixed point iterative method
The so-called fixed point refers to those points of x=f (x), and the so-called non-point iterative method refers to the original equation into x=f (x) Form, the next X value is the step f (x), so th
also has several methods, the following are more commonly used.GroupGroup ([Group1, ...]), str or tuple.Return subgroup (s) of the match by indices or names.For 0 returns the entire match.Groups (...)Groups ([Default=none]), tuple.Return a tuple containing all the subgroups of the match, from 1.The default argument is used for groupsThat didn't participate in the matchEnd (...)End ([group=0]), Int.Return index of the end of the substring matched by group.Start (...)Start ([group=0]), Int.Return
Code word is not easy, forward please indicate the original link
Before I talk about the Levenberg-marquardt algorithm, I want to talk about the Newton and Gauss-Newton methods first.Newton's Method If there is a bit of numerical computing knowledge of the students are not unfamiliar with Newton iterative method, first put a classic example map to the town build
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