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最近看的影集及電影(雷)

這幾天，因為網友推薦，看了關於我轉生變成史萊姆這檔事
看完第一季，覺得還不錯，只是推薦我看的網友，知道史萊姆是什麼，
但是居然沒有聽過勇者鬥惡龍這個遊戲。
我和網友都懷疑，主角會不會變成最後大魔王，要跟勇者對決？

今天，為了消秏MOD的看片金，看了 詐騙女神 這部片，
覺得還OK, 好在最後的走向我有喜歡，如果變成純愛劇，
我會覺得很爛…

0/0未定義的原因 (小學數學)

0/0是未定義，那為何0/0不是1呢？是否有反例？
我想到的反例如下：(這是我自己想的，如有錯誤，還請指正)
Assume 0/0 = 1,
if 2x = 3x
=> x = 1.5x, so x = 0
=> 0 = 1.5 * 0
兩邊同除0
=> 0/0 =1.5 * 0/0
=> (0/0) = 1.5 * (0/0)
We assume 0/0 = 1
=> 1 = 1.5 * 1
=> 1 = 1.5, 所以這是0/0 = 1的反例

那麼0/0是否等於0呢？
這個我不知道真正的反例，
但是這樣0/0就不能上下消去得到1了。
至於0/0等於其它數值，可以簡單得到反例，
這就不提了。

Differential and Partial differential

Differential of a function

where ${\displaystyle f'(x)}$ is the derivative of f with respect to x, and dx is an additional real variable (so that dy is a function of x and dx). The notation is such that the equation

${\displaystyle dy={\frac {dy}{dx}}\,dx}$

holds, where the derivative is represented in the Leibniz notation dy/dx, and this is consistent with regarding the derivative as the quotient of the differentials. One also writes

${\displaystyle df(x)=f'(x)\,dx.}$

satisfies

${\displaystyle \Delta y=f'(x)\,\Delta x+\varepsilon =df(x)+\varepsilon \,}$

where the error ε in the approximation satisfies ε/Δx → 0 as Δx → 0. In other words, one has the approximate identity

${\displaystyle \Delta y\approx dy}$

in which the error can be made as small as desired relative to Δx by constraining Δx to be sufficiently small; that is to say,

${\displaystyle {\frac {\Delta y-dy}{\Delta x}}\to 0}$

as Δx → 0. For this reason, the differential of a function is known as the principal (linear) part in the increment of a function: the differential is a linear function of the increment Δx, and although the error ε may be nonlinear, it tends to zero rapidly as Δx tends to zero.

the partial differential of y with respect to any one of the variables x₁ is the principal part of the change in y resulting from a change dx₁ in that one variable. The partial differential is therefore

${\displaystyle {\frac {\partial y}{\partial x_{1}}}dx_{1}}$

參：

https://en.wikipedia.org/wiki/Differential_of_a_function

全微分和偏微分有什麼不同

假設 z = x^7 + y^3 + 3(x^2)*(y^4) + 4xy + 98 
z為應變數 , x y為自變數 

全微分 : 
就是所有變數通通都要微分 
dz = 7x^6dx + 3y^2dy + 6x(y^4)dx + 12(x^2)*(y^3)dy + 4ydx + 4xdy + 0 
ps. 兩變數相乘的 , 如同一般乘法的微分 , 前微後不微+前不微後微 

偏微分 : 
只對要微的自變數微分 , 其他的都當作常數 
1.對 x 偏微 
∂z/∂x = 7x^6 + 0 + 6x(y^4) + 4y + 0 

2. 對 y 偏微 
∂z/∂y = 0 + 3y^2 + 12(x^2)*(y^3) + 4x + 0

參：

https://tw.answers.yahoo.com/question/index?qid=20050930000013KK04937

pdf2txt

pdf2txt.py

pdf2txt.py从PDF文件中提取文本内容。它提取所有要以编程方式呈现的文本，即以ASCII或Unicode字符串表示的文本。它无法识别绘制为需要光学字符识别的图像的文本。它还为每个文本部分提取相应的位置，字体名称，字体大小，书写方向（水平或垂直）。访问受到限制时，您需要为受保护的PDF文档提供密码。您无法从没有提取权限的PD文档中提取任何文本。

$ pdf2txt.py -o output.html samples/naacl06-shinyama.pdf
(extract text as an HTML file whose filename is output.html)

$ pdf2txt.py -V -c euc-jp -o output.html samples/jo.pdf
(extract a Japanese HTML file in vertical writing, CMap is required)

$ pdf2txt.py -P mypassword -o output.txt secret.pdf
(extract a text from an encrypted PDF file)

有关详细信息，请参阅/docs/index.html。

PDFMiner.six

PDFMiner.six is a fork of PDFMiner using six for Python 2+3 compatibility

 

PDFMiner is a tool for extracting information from PDF documents. Unlike other PDF-related tools, it focuses entirely on getting and analyzing text data. PDFMiner allows one to obtain the exact location of text in a page, as well as other information such as fonts or lines. It includes a PDF converter that can transform PDF files into other text formats (such as HTML). It has an extensible PDF parser that can be used for other purposes than text analysis.

• Webpage: https://github.com/pdfminer/
• Download (PyPI): https://pypi.python.org/pypi/pdfminer.six/

Code using pdfminer:

from pdfminer.layout import LAParams
from pdfminer.converter import PDFPageAggregator
from pdfminer.pdfinterp import PDFResourceManager, PDFPageInterpreter
from pdfminer.pdfpage import PDFPage
from pdfminer.layout import LTTextBoxHorizontal
import sys, os

os.environ["PYTHONIOENCODING"] = 'utf-8'
sys.stdout.reconfigure(encoding='utf-8')
#print(sys.stdout.encoding)
#print(os.environ["PYTHONIOENCODING"])
            
document = open('Pfizer1.pdf', 'rb')
rsrcmgr = PDFResourceManager()
laparams = LAParams()
device = PDFPageAggregator(rsrcmgr, laparams=laparams)
interpreter = PDFPageInterpreter(rsrcmgr, device)
for page in PDFPage.get_pages(document):
    interpreter.process_page(page)
    layout = device.get_result()
    for element in layout:
        if isinstance(element, LTTextBoxHorizontal):
            obj = element._objs[0]
            print("x_cor: %.2f " % obj.bbox[0])
            print("y_cor: %.2f" % obj.bbox[1])
            print("length: %.2f" % obj.bbox[2])
            print("height: %.2f" % obj.bbox[3])
            text = obj.get_text().replace('\n','')
            #btext = text.encode(encoding='utf-8')
            print("text: ", text)
            print("--------------------")