plot – Find the unknown coefficient using contour drawing

I have a very complicated equation, but for the sake of simplicity, let's assume that my function is F (x, y, z) = ax + by + c * z, where a, b and c are unknown constants.

Experiments we know that at:

x = 3, y = 2, z = 1 then F = 10

x = 2, y = 1, z = 0 then F = 4

x = 1, y = 0, z = 0 then F = 1

So, is there a way to plot F (x, y, z) as an outline plot and then adjust my data above to extract the exact unknown coefficient?

By the way, the sample answer is a = 1, b = 2 and c = 3.

How does the Zcash wallet software find its own balance if I use an armored address?

Zcash is composed of a public address and an armored address.

Armored address is perfectly hidden all transaction activities.

So, how does the Zcash wallet software (or explorer) find the balance of shielded addresses?

Find out who is the user who checked out a folder

I can not delete a folder because a user has extracted to this folder.

The folder is blocked for editing.

How can I discover the user who checked out? so that I can contact him.

Equation Resolution – How to find the distances between two adjacent maxima in a solution of NDSolve

I'm trying to find a general approach to trace the temporal evolution of horizontal distances from maximum to maximum in a solution of EDP. The solution u[x,t] normally have several maximum and minimum in the space xwho are moving in space x and evolve over time t.

Here is a simple example in which the maxima and the minima are periodic. But in my real problem, they are not periodic and the distances between different pairs of adjacent max are different at one time. t, the distances between two adjacent max may also change t.

sol = NDSolve[{D[u[x, t], t] + u[x, t] D[u[x, t], x] + D[u[x, t], x, x] + 
0.4*D[u[x, t], {x, 3}] + D[u[x, t], {x, 4}] == 0,
u[-4 [Pi], t] == u[4 [Pi], t], u[x, 0] == 0.1*Sin[x]}, u, {t, 0, 20},
{x, -4 [Pi], 4 [Pi]}]

Plot3D[Evaluate[u[x, t] /. First[sol]], {t, 0, 10}, {x, -4 Pi, 4 Pi}, PlotRange -> All, PlotPoints -> 100]

enter the description of the image here

I tried to use Table[FindMaximum[Evaluate[u[x, t] /. First[sol]], {x, x0}][[2, 1, 2]], {t,0,tend,0.01}] with an initial position x0 to find a local maximum. But I do not know how to simultaneously find two adjacent maxima to trace the temporal evolution of their distance.

Trying to find the time value changed in postgresql

I have a table that has an identifier, a value and a date. There are many identifiers, values ​​and dates in this table.

The records are inserted periodically in this table. The identifier is unique but the value changes sometimes.

How can I write a query that will give me the ID plus the last time the value has changed? Note: The value may reappear, for example from 1 to 2, then back to 1.

How to find Substring without integrated function in javascript?

function myFunction(num1, num2) {
  var str = "This is a string";
  var subString = "";
  var len = str.length;

  if (num1 < 0 || num2 > len) {
    console.log("Invalid input");
  } else {
    var k = 0;
    for (i = num1; i < num2; i++) {
      subString = subString + str(i);
myFunction(0, 4);

Editing – How to properly find the slope of a linear part on LogPlot

I need to draw an interpolation function of an independent variable (only a 3 KB file) on LogPlot and show the slope of its linear part on a LogPlot. But when I Show the LogPlot and a line with the slope of the linear part, it proved incoherent.

  1. import data and plot:

    data = <<"...\data.m";
    logPlot = LogPlot(data(t), {t, 0, 2}, PlotRange -> {{0, 2}, {0.01, 30000}}, Frame -> True)

enter the description of the image here

  1. Observe the range of the linear piece and find a linear fit:

    data = Table(Log(data(t)), {t, 1, 1.2, 0.02});
    linearpart = Fit(data, {1, t}, t);
    (*0.923913 + 0.689265 t*)
  2. Show together

    Show(logPlot, Plot(linearpart, {t, 1, 1.2}, PlotStyle -> {Red, Dashed}))

What is the problem with that. Please help.

raspberry pi – Where can I find a useful newspaper if bitcoind has stopped for no apparent reason?

I run bitcoind (Bitcoin Core) on a Raspberry 3B and the process "disappears" from the list in top. The newspaper debug.log does not show any streaks, the last entry is usually something like

2019-11-08T20:21:33Z UpdateTip: new best=0000000000000000001dd32ef554a1bb9e204d6f46ab345302019412ac2f6af9 height=506280 version=0x20000000 log2_work=87.972007 tx=295647959 date='2018-01-27T01:16:11Z' progress=0.631698 cache=13.3MiB(59241txo)

What could be a reason and where could I look?

My configuration for my low memory system is:

 $ cat bitcoin.conf

# is required by Fail2Ban described below
# magic RBP optimisations

# running without swap



dynamic programming – You have K amoebas and an amoeba can divide into A, B, C amoebas after an instruction and then find the minimum. of instruction to have N amoebas

. You have developed an artificial amoeba and you can control exactly how it divides.
Each amoeba may be responsible for splitting into amoebae A, B or C. This
is, if you ask an amoeba to divide into A, that amoeba will disappear, and A
different new amoebas will appear.
You start with K amoeba at first, and you want to give them instructions
so that in the end you only have N amoeba left. Giving an instruction is a
expensive deal because it requires you to produce biochemicals, and you want
give the least possible instructions. Find and write the minimum number of
instructions you should give to find yourself with exactly N. amoebas. If it can not
to be done, write 1 instead. Note that each instruction is given to a single amoeba,
and not all together.
For example, suppose that K = 1, A = 1, B = 2, C = 3, N = 4. Then you can take
Simple amoeba, ask him to divide into amoeba B (2). Now there are 2 amoebae.
Then take one of these amoebae and ask him to divide into amoeba C (3). So
Now you have 4 amoebae in total, what we want, and we used 2 instructions.
You can check that you can not get 4 amoebae with less than 2 instructions, and
so 2 is the minimum, so the answer is 2.
Find the minimum number of necessary instructions for these instances:

(a) K = 23, A = 7, B = 12, C = 16, N = 114
(b) K = 9, A = 7, B = 15, C = 16, N = 76
(c) K = 10, A = 9, B = 12, C = 26, N = 138

I will find some uncompetitive and long tail keywords that will actually rank your site for € 5

I will find some uncompetitive and long-tail keywords that will actually rank your site

I am an SEO expert and in general, people say that I have written many articles on my website but that their websites are not visible in the search engine and that they are then at the 50th or the 60th position. So I come. I will find uncompetitive keywords for which you can write your content. You will then see that your content / website actually ranks in the competitive landscape and that it appears in the competitive landscape (the top 20 search engine search results).

. (tagsToTranslate) Keyword (s) Search (t) SEO (t) OnPAge (t) LongTail (t) Low