Math / Science

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

Share tech news, updates, or what's on your mind.

Sign up to Post

Here is the code

Function EIGEN_JK(ByRef M As Variant) As Variant

'**  Function computes the eigenvalues and eigenvectors for a real        **
'**  symmetric positive definite matrix using the "JK Method".  The       **
'**  first column of the return matrix contains the eigenvalues and       **
'**  the rest of the p+1 columns contain the eigenvectors.                **
'**  See:                                                                 **
'**  EIGENVALUES OF A REAL SYMMETRIC MATRIX", The Computer Journal,       **
'**  VOL.15, 271-273.                                                     **

Dim A() As Variant, Ematrix() As Double
Dim i As Long, j As Long, k As Long, iter As Long, p As Long
Dim den As Double, hold As Double, Sin_ As Double, num As Double
Dim Sin2 As Double, Cos2 As Double, Cos_ As Double, Test As Double
Dim Tan2 As Double, Cot2 As Double, tmp As Double
Const eps As Double = 1E-16
    On Error GoTo EndProc
    A = M
    p = UBound(A, 1)
    ReDim Ematrix(1 To p, 1 To p + 1)
    For iter = 1 To 15
        'Orthogonalize pairs of columns in upper off diag
        For j = 1 To p - 1
            For k = j + 1 To p
                den = 0#
On Demand Webinar: Networking for the Cloud Era
On Demand Webinar: Networking for the Cloud Era

Ready to improve network connectivity? Watch this webinar to learn how SD-WANs and a one-click instant connect tool can boost provisions, deployment, and management of your cloud connection.

The probability formulas are to be used for wagering on harness racing. There are 6 types of wagerings:

1. Win: You wager on that a certain horse will win the race, and there might be 12 horses in the field.
2. Place. You wager on that a certain horse will end 1st, 2nd or 3rd in the race.
3. Twins: You wager on that two horses in the field will end 1st and 2nd irrespective of the order in the race.
4. Trio: You wager on that three horses will end 1st, 2nd and 3rd in exactly that order in the race.
5, Top 7 Pro: You wager on that 7 horses end 1st, 2nd, 3rd, 4th, 5th, 6th and 7th in exactly that order in the race.
6. DD: You wager on that a certain horse will win race 1 and a certain horse will win race 2.

So type 1-5 are for only one race, whereas type 6 is for 2 races.

Type 1 is not difficult: If there are 12 horses in the race, then each horse has a 1/12th chance to win (8.3 %) if they would have exactly the same capability.

What would the function be for the other five types, assuming there are always 12 horses in the field?

Logically the order of most easy to most difficult would be this:

2. Place
1. Win (difficulty/probability 8.3 %)
3. Twins
6. DD
4. Trio
5. Top 7 Pro

Which formulas could I enter in this online probability calculator for example?:
Can you please explain this question?

1. What value or values of ml are allowable for an orbital with l = 2?
a. 0
b. 2
c. -1
d. none of the above
e. all of the above
Does any one knows a web site where can I practice the nomenclatures?
Is there a tool to calculate line checksum of motorola S3 Record ?

For example, following is line of motorola S3 Record:


To calculate checksum manually, one byte of size, four bytes of address, and all data bytes are summed.  Extract least significant byte
from the sum, take it's one's complement and that's the checksum.

Is there a checksum calculator or tool that will calculate the checksum ?
Imagine you have a dataset of rowers. You have X variables such as weight, benchpress, deadlift, squat, nutrition, etc. You also have each rower's lap time.

Now, let's say for a given rower, you want to optimize her lap time, but you can only train along ONE DIMENSION. How would you identify the best attribute to optimize?

I thought about a grid search, but that seems awful. Which family of machine learning algorithms would be best for this type of problem, and how would you attack it?

Thanks a million!
Can someone help with this?

Let p = 4x - 7

Is the below equation equivalent to (4x−7)^2 + 16 = 40x - 70 in terms of p ?

p^2​​ −10p+16=0
Hello Experts!

Please bear with me, as I start from the beginning...

The Setup:

(Real details have been removed)

Our customers have the ability to print their artwork/logo on 10x10 sheets of paper. Through the years, we have converted many printed jobs.  So I have a dataset that includes:

  • Product Dimensions
  • Artwork Dimensions

With knowing that information, I can calculate the '% of Ink Coverage' for each printed job.

So for example,... "Our customer printed a 5x5 logo, on a 10x10 sheet of paper. Thier % of Ink Coverage is 50%".

The Problem

The overwhelming majority of our customers, do not know artwork dimensions at the time of quoting. As you can imagine, determining a price can be very difficult.

As of today, in order to still offer a quote to our customer - we quote them: 10x10 sheet of paper with a 2x2 artwork dimension.

The major flaw with this approach,... is the 2x2 artwork dimension we are quoting - really is just a guess. (Maybe not a complete stab in the dark but I know we did not take a close look at historical data to determine this 'temporary' artwork value)

The Goal

While it's near impossible to guess the exact printed dimension our customer will ultimately use, it's our goal to suggest dimensions that will be close to or OVER what the customer will most likely choose at the time of order.

(Before final artwork was received)
10x10 …
available lengths of four sides  are AB 06 meter,BC 14 meter  CD  01  meter and DA  15 meter ,
whats the area of this plot ,in a calculation i got 0.3027040  cent . is it  correct ?

Modern healthcare requires a modern cloud. View this brief video to understand how the Concerto Cloud for Healthcare can help your organization.

If I raise a number to the power of five the last digit of the result is always the same as the last digit of the number with which I started.  For example  7^5 = 16807.  The last digit of both numbers is a five.
Are there any rules regarding when the last 2 digits are repeated?  For example 25 is always repeated.  I don't think 12 is ever repeated.
How can I solve these kind of problems in my brain without using pencil and calculator?

I have the Excel file below with 3 columns.
On one row I have a pair of q, k corresponding to a certain x.
In the sheet are different values for x.
I need to find what pairs of q, k are common for all values of x.
How do you do that fast and easy?
What is the best and easiest approach, method, software to solve a system like the one below?


Could you help to find a set of solutions? I guess are more than one.
This is not homework, but rather one of that engineering approximation problem that ended up in a set of unknown variables.

Basically the function is.
with p, q, k, r, s unknown.
And next known set of solutions with 1 digit approximation allowed for S5x:
x - S5x
1 - 0
2 - 1
4 - 2
8 - 3
16 - 6
32 - 13
64 - 25
128 - 50
256 - 101
512 - 201
1024 - 401
2048 - 799
4096 - 1567
8192 - 2896
16384 - 4096
Can you please tell me if the calculations are correct?
An interesting perspective on why Russia seems to have a higher representation of hackers as compared to the US:

This article focuses primarily on how Russia has integrated computer science into school curriculums at much earlier grade levels than the US. On top of that, there are less opportunities (ie. Silicon Valley) in Russia for leveraging this education. It doesn't really delve into the "hacker" aspect, but shows that Russia has twice the amount of students taking AP Comp Sci exam as the US.

I think they've missed the mark a bit in only focusing on the education aspect, as many countries have great developers, but it's rare that you see them represented in the more malicious side of dev work.

Back in the early 2000's when I was focused heavily on affiliate marketing, I'd often see hacking of affiliate sites (for malicious cookie stuffing) and Adwords accounts (for rogue PPC ad groups) via Russian groups regularly and didn't understand why it was so prevalent.

After speaking with a friend who grew up there, I asked why he thought there was such a high volume of hackers coming out of Russia. His perspective was that "everyone steals, it's part of the culture and is one of the best ways to survive." One example that didn't click until he explained is how you see so many dash cam videos from Russia
I am trying to check integration using two different methods, first by using [function (int)] and second by using summation. I am integration from high to low values (0.1 to 0). I got same result. However, from function I got positive value (0.005) and from summation, negative value (-0.005).  I am not sure if that because I am integrating from high to low values so I need to use (dr) in negative value when finding the integration using summation.

I used below code

 clear all;
  syms x y 
  y = -x; 
  for i=1:20

Open in new window

I see this cool animated GIF that shows a prism refracting light. Can the light also go the other way, and make the light more focused?

Is it true that a prism that refracts light as well as focuses light?

I am trying to rotate an object and get the following error message: 1119:access of possibly undefined property Math through a reference with a static type class. Thank you for your help

 here is the code


stage.addEventListener(MouseEvent.MOUSE_MOVE, FollowMouse);
function FollowMouse(event:MouseEvent):void
      var SideY:Number = mouseY-circle.Y;
      var SideX:Number = mouseY-circle.X;
      var Rad:Number = Math.atan2(SideY,SideX);
      var Deg:Number = Rad * 180/Math.PI;
      circle.rotation = Deg;
On Demand Webinar: Networking for the Cloud Era
On Demand Webinar: Networking for the Cloud Era

Did you know SD-WANs can improve network connectivity? Check out this webinar to learn how an SD-WAN simplified, one-click tool can help you migrate and manage data in the cloud.

Which is the strongest base for an antacid which works the quickest and is the most effective?
I'm trying to create illegal instruction reset.  

I'm programming Infineon TC29x Aurix Tricore Microcontroller based embedded system in 'C' language.  

I need to set program counter to illegal address, i.e. 0x00FF FFFC.  Can this be done with assembly language instructions?
If yes, please instrument assembly language instruction that would set program counter to 0x00FF FFFC while code is running.
I know I post a lot of article on here, but this is one you really should read.  Right now we are reaching the limits silicone.  The smallest transistors (that I have heard of) are just 7 nm (7 atoms wide).  At this point it becomes very difficult to make the transistor stable.  We are going to have to come up with a new material.  That's where quantum computing steps in.  It uses qubits , small particles that are smaller than an atom.  Unlike traditional computing, a qubit can exist as both a 1 and a 0 at the same time.  Again it is very hard to make them stable, but as we continue to increase them it will be the next big jump in computer technology.  And this one will make the jump from vacuum tubes to the transistor look like a pinprick!,34434.html
LVL 56

Expert Comment

I think you mean silicon, not silicone.

Author Comment

you are correct, sorry about that.
a car travels 100km in 50 minutes.what will the speed be in km\h
I would like to implement a fast fixed point sine approximation for PIC24F microcontrollers on 16bit.
I started from here:
The approximation is done with polynomials: 3rd order up to 5th or even 6th order.
I am stuck in the beginning.
The 3rd order polynomial is S3(x)=(3/PI)*x-(4/PI^3)*(x^3) or S3(z)=(1/2)*z*(3-z^2) with z=x/(1/(2*PI))
I tried an Excel sheet for this function and I compared with sin() from Excel.
Either I make a mistake or the approximation error is too big.
Here is the Excel: 
Could you help to debug this?
I have a client who has an issue getting the LINEST() function to work for them.  This is my first time using LINEST(), and what seemed, at first, to be straightforward has deepened considerably in levels of complexity.  I am an accomplished VBA programmer, and I feel the best way to give the client what they need is to duplicate the equation in VBA to calculate the slope (m) when there are multiple X Axes.  When only one X axis exists, I have validated LINEST against my own independent calculation, as shown by the equation below.

slope (m) calculation for single X Axis
I am looking for a similar equation I can apply, given 2 or more X Axes.  Reproducing the underlying query in VBA will make for a much more versatile function, capable of calculating LINEST in a more wide-ranging set of circumstances than Excel currently allows, thus meeting my client's requirements.  For those not familiar with LINEST(), I have included a couple of sites that have given me the best start on solving the problem.  The office support site provided the equation, as shown above, which gave me a reliable means to have an independent check against the Excel function on a single X axis.  Every site I've seen thus far provides the LINEST() equation for multiple X Axes, but nowhere have I seen a more nuanced formula that tells me what Excel is doing to derive that number.  That's my missing piece.

Thanks, in advance, for your support.  ~ Peter Ferber

Math / Science

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