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Questions tagged [numerical-value]

Question relating numerical representations, operations and methods, including approximate results instead of exact symbolic results.

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Numerical Integration limits - Infinity works fine, Large finite upper limit does not

I am calculating an integral with NIntegrate from a lower finite limit to infinity. The integrand contains logarithms and square-roots. It has a pole at some point, and I substract the denominator at ...
Xorker's user avatar
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51 views

A problem with obtaining the beam frequencies and mode shapes

I am supposed to find the mode shapes of two assembled beams. To this end, we must reduce the PDE equation of motion of beam to an ODE including the oscillation frequency. The solution of ODE has some ...
Sajad Mirhashemi's user avatar
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29 views

Non-numerical values in double numerical integration [closed]

I am integrating twice numerically, and in my case I cannot use the inbuilt double numerical integration. I am getting an error message about non-numerical values and I broke it down to the minimal ...
Xorker's user avatar
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NDSolve::litarg error and overdetermined system error in NDSolve

Before the long description about my problem, my question is How can I avoid NDSolve::litarg error and overdetermined system error in a NDSolve for simultaneous differential equation. Nowadays I ...
chickenstick's user avatar
1 vote
0 answers
66 views

Problems with implementation of subresultant pseudo-remainder sequence in Sturm's theorem

I've implemented the subresultant pseudo-remainder sequences ( https://en.wikipedia.org/wiki/Polynomial_greatest_common_divisor#Pseudo-remainder_sequences ) as described in Wikipedia. However, when ...
Moonwalker's user avatar
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1 answer
54 views

NSum with variable sitting inside

I want to evaluate the following and many other similar expressions numerically from k=2 to k=Infinity with a variable ...
QFTheorist's user avatar
0 votes
1 answer
95 views

Solving a 3+1D Wave Equation

I am having some problems with finding the solution to the magnetic field, B[x,y,z,t]. Is there anything I can change to my code to obtain a solution of B[x,y,z,t] with the initial conditions and ...
Tommy Wong's user avatar
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0 answers
42 views

How to find optimal solution

I want to ask something. Right now, I want to try to find the optimal solution from a function in a paper. here is the function : And here is the numerical example : There is solution procedure that ...
Grizzly54's user avatar
3 votes
2 answers
40 views

Strange behavior of MinimalBy [duplicate]

data = {{1, 2}, {2, 2}, {3, 3}}; MinimalBy[data, Norm@# &] Output: {{2, 2}} When applying numerically : ...
lesobrod's user avatar
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2 votes
0 answers
55 views

Interpreter fails to obey significant figure specifications

Consider the following example, where we specify the precision of the numbers to perform a significant figures calculation: ...
Joshua Schrier's user avatar
2 votes
1 answer
106 views

Finding roots for an expression with non-elementary function

Is there an approach to solving this for $a$ in either closed-form or numerically? ...
Moo's user avatar
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0 votes
1 answer
67 views

How to use multiple output from Nsolve? [closed]

I have 3 simultaneous equations and 3 unknowns. The values are coming to be right. But how do I assign these 3 values in the respective variables? ...
Sheersha Karmakar's user avatar
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2 answers
139 views

How to numerically find complex non-real roots of a function?

Using Mathematica, how can we numerically find only complexes, but not real roots, of a function? For example, if we have f:C->C, and we have roots like, R1,R2,...,Rn (real roots, without imaginary ...
GarouDan's user avatar
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1 vote
0 answers
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How to Parse Binary .STL File Created on Ancient 32-bit Architecture

Import[fileName,"STL"] returns $Failed The file format is so simple that one can calculate the number of triangles in the file by counting the number of BinaryReads to reach EndOfFile. https:...
Stewart Dickson's user avatar
1 vote
1 answer
114 views

Can't solve equation numerically (Solution in terms of Root) [duplicate]

I am trying to solve the following equation numerically. ...
dorrel's user avatar
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2 votes
1 answer
130 views

Solving a ODE (Peeble's Equation) with initial condition a the maximum input range

I have a differential equation which is, $$ \frac{d X_e}{dz} = \frac{C_r(z)}{H(z)}\times \frac{1}{(1+z)}\Big[\frac{38\eta T^3}{25\pi^2}\alpha (T)X_e^2 - b(T)(1 - X_e) \Big] $$ Where $$ \alpha(T) = \...
Kazi Abu Rousan's user avatar
1 vote
1 answer
64 views

Is a four-variable function less than one?

I have the following function of four variables f=Sqrt[(1 + w - x + 4 y z) - Sqrt[4 (-w + x) + (1 + w - x + 4 y z)^2]]/Sqrt[2] I want to show that $f(w,x,y,z)<1$...
Julio Abraham Mendoza Fierro's user avatar
3 votes
0 answers
61 views

Derivative[0, 1, 1][QPolyGamma] cannot be calculated numerically?

During a more complicated calculation, I got an expression ...
Vaclav Kotesovec's user avatar
0 votes
2 answers
106 views

Why can't NSolve find values that FindInstance can?

I am trying to solve for \[Epsilon], given three input paramters n, x and ...
Dotman's user avatar
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5 votes
1 answer
180 views

Why is Around omitted when the uncertainty is zero?

I have a list of values with errors and I use Around[x, dx]. Some of those values have an error of zero though. Mathematica removes the ...
Failboy's user avatar
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0 answers
67 views

NSolve can't solve a system of 2 equations with 2 unknowns

I've been trying to solve a system of 2 equations with 2 unknowns using NSolve. But It's been too slow. I waited for more then an hour without any results. The code is: ...
Alen's user avatar
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38 views

How to treat small numbers in order to gain efficiency and precision in neural network algorithm?

Unfortunately I won't be able to provide a MWE, as it would be too big and complex, and this question will be based on pure semantics, basically (and I understand if this is impossible to answer in ...
GaloisFan's user avatar
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1 answer
107 views

NMinimize can not find points that satisfy constraints

NMinimize cant find solutions for a function which clearly has one. Setting a working precision resulted in some output, however with error messages about tolerance and precision. Heres my code. The ...
Dotman's user avatar
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1 vote
0 answers
65 views

Numerical Error using compile

I'm trying to compile a function and I'm running into the following error CompiledFunction::cfne : Numerical error encountered; proceeding with uncompiled evaluation. I think I have succeeded in ...
Dotman's user avatar
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0 votes
1 answer
116 views

Performance improvements using Table and Compile

I'm converting a code from MatLab to Mathematica. It takes MatLab less than a second to compute it while its more than ten minutes in Mathematica. I was hoping to improve the performance. Here's a ...
Dotman's user avatar
  • 456
-2 votes
1 answer
68 views

How to make faster of a code containing more iteration point? [closed]

I am trying to evaluate a code of the Power Series Solution method to get the results. Also, the time of evaluation depends on the parameters I am using. When the iteration point is 50, 60, or 80, it ...
supragyan priyadarshinee's user avatar
1 vote
2 answers
166 views

How to make faster of a code containing more iteration points?

I am trying to evaluate a code of the Power Series Solution method to get the results. Also, the time of evaluation depends on the parameters I am using. When the iteration point is 50, 60, or 80, it ...
supragyan priyadarshinee's user avatar
0 votes
1 answer
119 views

How to minimize numerical error in the code while solving the system of ODEs

I just want to ask in the graph of the code mentioned in the link, while plotting u from {-0.0001,y,0.0001}, the jump is coming because of the numerical error u1-u2. Can anyone please tell me, how to ...
Komal Goyal's user avatar
1 vote
2 answers
159 views

Finding closed form representations of floating point numbers?

Is there a trick to automatically recognize that ${-0.5771,1.2280}$ are approximately equal to {-EulerGamma, Log[2 + Sqrt[2]]}? These were obtained by using ...
Yaroslav Bulatov's user avatar
0 votes
1 answer
53 views

Proceeding integral or summation calculation with no explicitly designated quantities, but instead with an abstract 'n' quantities

Could someone kindly tell me how to calculate formulas such as integral or summation with no explicitly designated algebra quantities as derivatives or summands, but the abstract ' n' quantities ...
liqi3837671's user avatar
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0 answers
41 views

Nested NIntegrate with Matrix Exponential

I wish to perform a numerical integration which involves a matrix exponential. Here's the following code ...
kowalski's user avatar
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1 vote
1 answer
80 views

a problem in numerical integration in Mathematica

I am trying to numerically compute an integral of the following type in Mathematica. I can show that this integral can be computed analytically. Still, I want to make sure Mathematica can also give me ...
HadamardN2's user avatar
1 vote
0 answers
53 views

Increase computation speed for nested integral equations

I want to numerically solve these two nested integral equations $$q(J_0,T)=\int_{-\infty}^{\infty} \frac{1}{\sqrt{2\pi}}e^{-\frac{z^2}{2}}\,\mbox{tanh}^2\left(\frac{z\sqrt{q(J_0,T)}+J_0 m(J_0,T)}{T}\...
Ruth Murphy's user avatar
0 votes
0 answers
47 views

Identifying the parameter that flips the solution

I have solved a system of ODEs numerically. As the plot shows, the solution SolJx is positive for the parameters I have chosen. However, if you decrease (more ...
NC520's user avatar
  • 479
0 votes
0 answers
88 views

Error in numerical integration using Wolfram Mathematica

I hope you are doing well. I am having serious problems while calculating a numerical integral in Wolfram Mathematica, as the following error messages appear: 1- "Numerical integration converging ...
Rubens Filho's user avatar
1 vote
0 answers
78 views

Numerical solution system of ODEs

I want to solve the following system of ODEs with four boundary conditions: ...
NC520's user avatar
  • 479
1 vote
1 answer
195 views

How to numerically solve differential equations with singularities?

I wish to solve a differential equation numerically. As an example, I tried solving Hypergeometric differential equation ...
Erosannin's user avatar
  • 197
1 vote
1 answer
60 views

Value given by NIntegrate is double of Integrate function

I am performing a calculation where the result of NIntegrate and Integrate is different. They differ by factor of 2. Can someone tell what is the reason and how to make the NIntegrate value right?, <...
Kazi Abu Rousan's user avatar
2 votes
2 answers
212 views

Solving complex equation numerically

I'm trying to solve the following equation for $z$ for a set of given complex values of $a$ and for fixed $b$ (without providing any initial guess value(s)): $2^{iz}~\Gamma\left(\dfrac{iz+b}{2}+1\...
SCh's user avatar
  • 175
3 votes
2 answers
381 views

How can I speed up calculation of the integral?

Is it possible to speed up the calculation of the Kx integral? ...
Mam Mam's user avatar
  • 1,863
3 votes
1 answer
86 views

Why two the same integrals give different values?

Why two the same integrals give different values? ...
Mam Mam's user avatar
  • 1,863
1 vote
0 answers
64 views

How to solve this nonlinear partial differential equation stably?

I'm trying to solve this PDE with a numeric method. For an approximation, a radius $r$ that is sufficiently large (but not infinity) should be enough. When the coefficient of the initial condition $\...
Tao Guo's user avatar
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2 votes
2 answers
117 views

NMaxValue - function is not a real number

I'm trying to use NMaxValue to numerically find maximal values of the function F[z]. The problematic part of my code is as ...
cyndaquilka's user avatar
0 votes
2 answers
69 views

How to find the point where Exclusion starts?

I have two versions of a Plot ...
Patrick El Pollo's user avatar
2 votes
1 answer
68 views

What numerical error is Mathematica doing here and how can I avoid it? [closed]

So I am solving a system of equations in Mathematica: ...
Granger Obliviate's user avatar
2 votes
2 answers
150 views

How to get correct numerical result without lots of digit precisions?

I am wondering if it is possible to get the correct numerical result without computing with a lot of precisions in expressions. as a simple example suppose in the middle of some of my numerical code ...
ghadir jafari's user avatar
3 votes
1 answer
140 views

Shooting technique using NDSolve

Here I am attaching my code below. It took all the variable's values, but the graph window was empty. I am not able to recognize, where is the error exactly. Differential equations were also, checked ...
Komal Goyal's user avatar
0 votes
1 answer
66 views

Integration is not correct for the expression with a fraction?

What value Px2[16, 4] or N[Px22[16, 4]] is correct? ...
Mam Mam's user avatar
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0 votes
0 answers
33 views

How do I prevent, or get rid of the <code>Abs^\[Prime]</code> in the output of a partial of a Normalize[vector]? 12.0.0 for Microsoft Windows [duplicate]

12.0.0 for Microsoft Windows How do I prevent, or get rid of the Abs^[Prime] in the output of a partial of a Normalize[vector]? The code below shows the problematic ...
Steven Thomas Hatton's user avatar
5 votes
1 answer
139 views

Incorrect answer zero where correct answer is very large (precision issue)

Define a function F as follows: F[α_, x_] = N[Exp[x/2] Abs[Gamma[α/2 + I x /(2 Pi)]]^2, 10]; It is a product of two terms. ...
Laplacian's user avatar
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