# Math / Science

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The Math / Science topic primarily includes discussions of mathematics, physics, statistics and economic analysis, but also biology, chemistry and other sciences.

Any idea how find the partial fraction decomposition ?

Thx
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Hello and Good Afternoon Everyone,

This question is similar but not exactly like the one I have currently open.  Basically, I wish to know how to convert a number to a percentage.  The number of interest is total deductions.   To simplify my question here is a condensed hypothetical overview.  Gross Amount: \$1,924.70   Total Personal Deductions: \$424.05  Net Amount:  \$1,500.65.

If more information is needed, please feel free to let me know and it will be given.

Thank you

George

...
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So I must disclaim that I know that this is not an idea solution, however wanted to get some science and technical terms correct for running two networks off one NIC card as a work around to having VLAN and/or second router.  Again, this is NOT how I would do things, but for some home user wanting to run lets say a network off of another network for testing that it can be done this way because of how layer 2 works.  The layer 2 part is what I am most interested in, but wanted to get some expert opinions and why it works.

So a home user has a PC that is hooked into a dumb switch.  The dumb switch then goes to a normal home router, however one port goes to a switch to a garage for instance.  The home network is 192.168.1.0 and the garage is 10.10.10.0 that runs some devices that do not need internet.  Just needs to be able to send and receive data, and those devices might have another device down the line like a switch with more devices.  Now I know that you can set the NIC card on the computer to be the main IPv4 of 192.168.1.10 255.255.255.0 192.168.1.1 8.8.8.8 etc on the main page and on the advanced tab you can add a secondary IP of 10.10.10.10 255.255.255.0 no gateway and it will route the traffic to that network with zero issues and normal LAN traffic will go out the other direction.

I guess call it a proof of concept, but it allows this happen because it is only doing layer 2 and switched go off of MAC addresses so that traffic will never hit the router for this …
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Hello and Good Afternoon Everyone,

I wish to help a friend with a percentage question as it relates to his payroll check.  Basically, he wishes to know the percentage of deduction for a bonus in the amount of \$1,000.   In other words, he wishes to know how much of the \$1,000 he keeps.  To aid in the computation, here is a brief summary of details:  Gross Amount:
\$2, 891.84.... Net Amount:  \$1,933.81..... Total Personal Deductions: \$958.03.  The bonus of \$1,000 was combined with his regular pay to make one check as opposed to it being a separate payout.

If more information is needed in computing the percentage of deduction for the bonus, please let me know and it will be provided upon request.  That said, I look forward to hearing back from everyone regarding this question.

Thank you

George
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I have a cash projection model in Excel.
I have around 10 years of monthly data.
There are around 10 sources of cash and around 10 uses of cash.
I have determined the type of distribution which best fits each of the 20 series.
I have calculated the pertinent statistical parameters of each of the 20 series (e.g. mean or mode, standard deviation, etc.)
I have fitted the selected distributions with their respective parameters.
Some of the series have a normal distribution around a relatively high mean value.
Some of the series have a more Rayleigh or Weibull distribution - always positive but not symmetrical.

The purpose of the model is to predict the cash position over each of the next 12 months.
In some cases, a series has a growth factor to be included.

Each month, for each series, the current actual value is appended resulting in a new series of actual values.

Then an expected value is calculated for each of the next 12 months.

The question is:
Given a random series with known distribution parameters, what is a good way of generating expected value predictions?

In some cases, it appears that the best prediction is the current value.
However, if there's an outlier in the current value, this doesn't work well.
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Determine the roots in the following case :
i. Square roots of i
ii. Square roots of (1+i)
iii. Square roots of 1+sqrt(3) i

Total no hints on how to solve the problem. ANy idea ?
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I need to use compression to change bit depth of a video signal.

Our Focal Plane Array(FPA) is Vanadium Oxide(VOx) Resistive Microbolometers Uncooled Thermal Infrared Detector.  The output of this image sensor is 14-bit, Wide Dynamic Range(WDR), raw, monochrome, 640 x 480 resolution.  The pixels of this video signal will be processed by Image Signal Processor(ISP).  ISP input is 12-bits.  Therefore, I need to compress FPA output to 12 bits and then input into ISP.

How to perform global tone mapping using two methods, PWL and LUT (curve defined by lut) based mapping.  I need to tone map 14 bit data to 12 bit.  What does PWL stand for?  Please provide sufficient information so I can achieve this.  It's suppose to be similar to gamma compression.  I can do gamma correction in matlab.  Can this tone mapping also be done in matlab?  If yes, please provide some examples.
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Please explain Gamma Compression algorithms. How to write Gamma Compression algorithms for typical video and image processing system?  Please provide some detailed examples.  How to gain sufficient understanding to be able to write Gamma Compression in 'C' or MATLAB?
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I was asked last night about performing maths with quadratic equations and I could show how to solve most problems but there was one that has left me completely baffled.  After about 45 minutes last night I had to give up.  (Probably missed something obvious and was making life way to complex for myself.)

4x.x - 35x + q = 0
what is the value of q.  One is also told the raltionship between two values of x which solve the equation.  Call those solution n and m then n = m squared (n = m.m).

I can use formulae from vieta to obtain things like m + n = 35/4 and m.n = q/4 and the formula for solving the quadratic but I then just get a horrendous mess with quadratic or higher equations when trying to simplify things.

Can someone point me in the right direction please.
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There are 39 numbered ping pong balls. The people who control the handling of the balls have a very complex way of making the draws 100% random.
The cash rewards are for 2-3-4 or 5 numbers.

The chances of one of our 5 numbers drawn in the first draw is 5 in 39 or 12.82% = ?
Then the chances of one of our other 4 numbers being drawn in round two would be 4/38 = 10.52% = ?

Their site says the chances for match 2 is 9.2%
3 = 1 in 95
4 = 1 in 3042
5 = 1 in 501.942

If four of our numbers have been drawn there are only 35 numbers left to be drawn. Why isn't the chance on the 5th number 1/35?
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Hi friends,

I have some visualisation project where textual info is displayed on a colored background (that is not disputable). The background color is meant to give a mental shortcut to the value, and it could be basically any color in the 3 byte RGB space. Nevertheless the textual info needs to be easily readable against the background.

I've found some algorithms to generate contrasting colors from background color by inverting (XOR with #FF) the R, G and B bytes of the background color, some with improvements for R/G/B values near 128. Unfortunately these algorithms generate some color combinations which are (to be very, very euphemistic) more insulting to the eye than mere unergonomic .

What I need is some algorithm that produces contrasting, but eye-friendly companion foreground colors out of the values of the background color values. (I'd take ready-to-use code, too ;-)

Any idea ?
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5 liters but they come in 4 packages --> \$11.95 - \$2.49 to give me 4 packages out of 5 .. not sure if I'm on the right track

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I've bought a sample test to practice my upcoming interviews.

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I don't know where to pu this question so I'm putting it under C# and .Net.

I have another interview on Friday and I was told there will be numerical logic whatever testing on a whiteboard. Ugh. I'm seriously thinking about saying I won't do it but of course I can't. Not that interested in the position so I might end up saying it. Why so some companies put the candidate thru the grinder?!

Anyway, I'm practcing some questions. Is the answer to this question 12?

How old is Jane ... if in 38 yrs... she will be 3 times as old as she is today?
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I have problems with coming up with the exact dollar match of \$3345.90 based on the original term of 5.87.  I need help with finding a better formula to get the total price match per the term months. A file that shows the formula I am using is attached.
Forumula-issue.xlsx
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What are some common conversational terms used when discussing the BigO notation?

I think this wold be a good way to give me more exposure to learn the meaning of common terms used when discussing the BigO notation.

Please provide as many as come to mind...

Thanks
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What performance consideration (for sorting) are there in .NET regarding various List Types? Arrays? Other?

What options are there when choosing a list type to use to hold large amounts of data? And what are the advantages of one of the other in a quick sort-time is required?

And, besides sorting, where would performance be a consideration?

Thanks
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How are elements grouped in the periodic table?
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The big terms of BigO Notation

I want to drill down into BigO, but hope to do so from a usefulness perspective. So, regarding making low-level algorithms more performant, for example. Or, from a memory management view...

Suggested topics to read up on? And a site where I can read this?

Thanks
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The diagonal length of the square from corner to corner is 19 inches.  Formula for the 4 equal sides of the square.
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Hi there.

I have trouble how to do this in STATA: I have a dataset with response (BOR) for the patients. The variable BOR can be CR, PR, SD, PD or NE. Each patient can be in either arm A or B. I need to make a table in STATA with the distribution of BOR on arm A and B, and I also need to calculate a p-value (log-rank) and Hazard ratio for each value of BOR.
Anyone who can tell me how to do this in STATA? If not STATA, when maybe the codes in an altertative statistics software? It's probably very much alike.

Best regards

Ulrich
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Why does a football fly better with a good spiral?
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Hello and Good Evening Everyone,

After reading this rather scientific intriguing article at  https://returntonow.net/2019/01/16/extinct-tree-brought-back-to-life-from-2000-year-old-seeds-archaeologists-found-in-a-clay-jar/?fbclid=IwAR07q4dEZr8c065jVS1Zr6NW6QDkVF70OSPHE6y05jrPQFVknt4dUIznksQ , I have the following question:  Is it possible to bring back to life an extinct species of tree by simply planting a seed of this extinct tree?   It seems to me that the seed would be dead and can not be expected to bring to life any species of tree or living plant.  But, could the seed itself be treated somehow scientifically and then planted in order to bring to life this extinct tree as indicated within the article?  Unfortunately, my scientific knowledge is merely limited to the general courses required to obtain my college degree in addition to never having a botany course per se.

Any shared thoughts regarding this question will be appreciated.

Thank you

George
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How many triangles are there

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# Math / Science

9K

Solutions

6K

Contributors

The Math / Science topic primarily includes discussions of mathematics, physics, statistics and economic analysis, but also biology, chemistry and other sciences.