# Tagged Questions

Questions on the use of numerical functions NIntegrate and NDSolve.

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### Integration problem: lrgexp

I want to calculate the following integration but it gives the error PolynomialGCD::lrgexp: Exponent is out of bounds for function PolynomialGCD. The code is: ...
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### Plotting NIntegrate

Plot[E^(-0.5 x) NIntegrate[Cos[t] E^(Cos[t] + 0.5 t), {t, 0, x}], {x, 0, 40}] Mathematica evaluates this integral for each point, which takes a long time. It is ...
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### Using a Mathematica index as a DiscreteVariable in NDSolve when solving a coupled set of ordinary differential equations

Context Since the explanation below of the problem to be solved is lengthy, let me preamble this by saying that I have code that works to solve the problem, but I don't know whether (1) it's ...
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### NIntegrate and Sum give different results in summing functions

I am using these two functions: ...
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### Numerical integral speed

I have the following code to calculate a numerical integral for any given a, however it takes a very long time, even with adaptivemontecarlo, which is not accurate enough: ...
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### A bug in Integrate

Integrate[(1 + 16 Tan[2 x - y]^2)/(1 + 4 Tan[2 x - y]^2), {x, 0, 2 π}] Mathematica (wrong) output is (tested under versions 8 and 10.0, took ~ 1 minute of CPU ...
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### Why does Mathematica say $\int_0^1\int_0^1\int_0^1\frac{1.0}{xyz}\,dz\,dy\,dx=0$?

Mathematica 9 says that $\int_0^1\int_0^1\int_0^1\frac{1.0}{xyz}\,dz\,dy\,dx=0$ and $\int_0^1\int_0^1\int_0^1\frac{1}{xyz}\,dz\,dy\,dx=0$. ...
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### Solving an integral equation numerically

my problem is: I get the result of definite integral and now I need to find the upper limit for the same integral but with opposite sign value so f2=-f1. ...
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### Forcing Exact Outputs for Integrate [closed]

I'm trying to compute the following triple integral: ...
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### Roots of two Functions containing integrals, with two parameters [duplicate]

I want to find the values of l1 and l2 from the following two equations: ...
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### Time evolution of a wave packet from the time-independent Schroedinger equation [duplicate]

Starting off with the time-independent Schroedinger equation (TISE) $\quad \quad -\frac{\hbar^2}{2m} \nabla^2 \psi + V(r, \theta) \psi = E\, \psi,$ I would like to study the time evolution of an ...
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### Integro differential eq boundary difficulties

I'm trying numericaly solve simple integro-differential equation, but have some problems with boundary conditions. System: ...
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### How can I perform this integration in Mathematica? [closed]

I am new to Mathematica. I want to find the integration of the following expression: $H(f)=T\left(\frac{sin(\pi f T)}{\pi f T}\right)^2$ Here, $T=1.127e-7$ I want to integrate this function for a ...
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### Detecting nearly simultaneous WhenEvents in NDSolve

I am trying to solve a system of (many) coupled nonlinear ODEs. I need to decouple some of the equations (i.e. set the time derivatives of some of the dependent variables to zero) at various points in ...
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### Evaluating a numerical integration with infinity as limit

I am trying to evaluate a numerical integration (to get an expression of the constant Ω) Suppose that h[x_] := 1/(1 + a x^2) ...
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### Fix my code to return a table of values

Here is a “procedural” program that we wrote in my class, implementing the rectangle rule of numerical integration: ...
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### Passing integration constants to self defined function

I would like to evaluate an integral I am taking in cylindrical coordinates, in which the integrand contains a previously defined function. I need to pass the r and phi integrand values to this ...