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John D'Errico


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5,126 2006 年以降の合計貢献数

(Don't contact me. I won't answer questions.) A retired mathematician, numerical animalist, woodworker, bridge player.

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Find the intersection points between two data sets
Finding the intersection point is easy enough. [intx,inty] = intersections(data1(:,1),data1(:,2),data2(:,1),data2(:,2)) intx =...

約9時間 前 | 1

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numerical solution of a system of ODE which is not in standard form
Your question seems to be one of solving a system of ODEs with a mass matrix. For example in the help for ODE45, we see this opt...

1日 前 | 1

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calculate tension by raphson newton in matlab
You have indicated these coefficients, although I worry there may be issues, because of the use of lower versus upper case W, et...

1日 前 | 0

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Interpolating n-dimensional functions
First, IF you have a complete gridded lattice, then you don't want to use griddatan. That is DEFINITELY a BAD idea. Why? Because...

2日 前 | 1

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What am I missing here?
Thank you. That makes it much easier for someone to offer you help. Now I'll be willing to look at the problem you had. It loo...

2日 前 | 1

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How to extrapolate a contour plot?
Let me see. You have data in only 25% of the region of interest. Now you want to extrapolate that data into a region that compri...

3日 前 | 0

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To solve non-linear equation by inversion notion
STOP. Is this nonlinear? Or is it linear? A*X = b is still LINEAR, even if the array is not square. Even in the linear case, t...

3日 前 | 0

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how to use reshape ?
The good thing about reshape is IF you put in an empty argument, then it figures out how many columns you will need. But first,...

3日 前 | 2

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Is an infinite for loop infinite?
We can always try it. Perhaps we can learn something about how the loop works, done by a careful test. Remember that doubles are...

4日 前 | 1

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how to fit 3 lines with one equation
Easy to answer. Is it possible? Of course. Anything is possible, though it may take a heck of a lot of work. I could even fin...

5日 前 | 0

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Image Processing on point clouds
If you want to use image processing tools, you pretty much need an image. Those tools are not written to work without one, certa...

5日 前 | 0

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Error in Eigen Values
Is KSr a double precision matrix, or a function, in the form of a function handle, or the name of an m-file function? That seems...

5日 前 | 0

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Multiplication of two polynomials having different variables
The simple answer is to use the symbolic toolbox. If you have it, I cannnot think of a good reason why you would not use it. sy...

6日 前 | 0

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geometric progression and multiply by a common variable, help me pls.
So, you want this? B = 3; C = B*20*sqrt(2).^(0:10) C = Columns 1 through 9 60 84.853 120 ...

7日 前 | 1

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f(x,y)<=0
I can see several ways off the top of my head. Consider some arbitrary implicit function. fun = @(x,y) x.^2 + y.^3 - 3; Easy ...

7日 前 | 0

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how to decode the message 67 44 41 49 39 19 113 76 62 104 69 55.
A good clue to the answer "Is this code correct", when applied to a homework assignment like this is if you get something that m...

8日 前 | 0

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Baseball trajectory with drag and wind
This is almost a classical problem, and the reason stiff ODE solvers were provided. Essentially, when you get that error using O...

8日 前 | 0

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Generating dispersed (non-integer) random matrix/array that sums to a particular value
I think you do not understand what you are asking. randfixedssum indeed produces results that are uniformly sistributed within...

8日 前 | 0

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What frustrates you about MATLAB? #2
That the mind reading toolbox has never become available for general use? ;-) Truly, that scares me just a bit if it ever truly...

8日 前 | 3

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Code to produce orthogonal rows in a N* N matrices
Not that hard. First check, is this homework? Hmm. Highly unlikely, since I had to think for at least a second about how to solv...

9日 前 | 2

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Double integration of a binomial function (in x and y) generated from two row arrays
I follow what you did (possibly) A = 10; B = 20; a = [0, 1, 2, 3, 4]; b = [5, 6, 7, 8, 9]; syms x y x = sym('x'); y = sym...

9日 前 | 1

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Bilinear and Trilinear Interpolation
Wow. I guess I've been working with those tools for so many years, as well as building variations of them, that I think of them ...

9日 前 | 1

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How to solve PDE problem
This is second order in the time derivative, so there is a utt term. But that should make in not in the realm of pdepe, which al...

9日 前 | 0

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1D Linear Elasticity Equivalent Stiffness Solution not being solved (6 equations and 6 vars)
These are differential equations, a boundary value problem. We use dsolve to solve it. For example, a simple example is: syms ...

10日 前 | 1

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Double integration of a binomial function (in x and y) generated from two row arrays
Let me explain, because you either have a simple problem to solve, or an impossible one. I've restated my comment as an answer,...

10日 前 | 1

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cubic interpolation vs spline interpolation vs cubic spline interpolation?
pchip is not a true cubic spline, in the sense that it is not a twice differentiable piecewise cubic interpolant. pchip is only ...

10日 前 | 0

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F solve error, how can I fix it?
There are no real solutions. First, I converted them to a problem that fimplicit can use. F1 = @(x,y) -(118/121)*x.^2-(333/242)...

10日 前 | 0

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find least squares parameters
Did you try polyfit? If not, then do so.

10日 前 | 0

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how to do the equation following its answer on matlab?
There is the obvious... Using y = 1/z, we can transform the problem. syms z y Fz = (1/z + 1/z^2 - 1/z^3)/(1 + 1/z + 1/z^2 + 4...

10日 前 | 0

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Got an Error Using Grid -Unknown Command Option
You don't get charged less for MATLAB, if you save on lines of code. They also don't charge less if you use another comma. You ...

11日 前 | 0

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