# Questions tagged [numerical-value]

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

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### Numerical evaluation after Normal? [closed]

I'm interested in numerical evaluation thru substitution: a /. a -> 1 (*=> 1 *) However if I used Normal in the "pipe" —...
96 views

### Numerical value of an expression with a uniform step size [closed]

I have a complex expression that is so difficult to separate its Real part from it Imaginary part. What I thought of doing is to get the numerical value of the Real and Imaginary part, Then I will use ...
361 views

### Specifying precision of a number in StringForm[]

I want to use StringForm to provide the headers to a table of numbers I have just calculated. Basically, I want the top row of spots in the table to have the form $D = x~~\text{(nm)}$, where x ...
266 views

### Visualizing the Schrödinger equation for dipole based interaction Hamiltonian

I want to evaluate and plot the solutions of coupled linear differential equations. For each time frame, I want to display the probability values (corresponding to mod square of these solutions), and ...
202 views

### Numerical Differentiation of a Numerical Integral

I am trying to evaluate the following expression numerically $$\frac{d^2}{dt^2}e^{-2t^2}\int_0^\infty\frac{\xi/\sqrt{2}}{\xi^{3/2}}e^{(-\xi^2/2-2\xi t))}$$ My code is as follows ...
94 views

### N[Product] and NProduct give different results

I have some trouble. I've been using finite product to study a certain function (see below). However, when I wanted to compute it precisely, I decided to use ...
90 views

### How to fix step size in do loop? [duplicate]

I apply the following command: Do[Print[var[u] = u], {u, -1, 1, 0.1}] It produces out put. But when i recall the value var[-0.4] as below: ...
295 views

### How to complete function which is not defined for all interval

I have a function testF22 like this ...
223 views

### Solving a complex equation

I try to solve a complicated equation. To do that, I write (excuse me, I could not copy paste in an appropriate way from the notebook) ; ...
123 views

### Numeric calculation with many digits

I try to calculate something like 1.569732312*Pi and by default mathematica returns something like 4.93146 (only 5 digits after floating point), but I believe there is much more digits, especially ...
114 views

### Why does this test yield True

I have this test implemented in my code, when I import a numeric matrix, which I thought would be bulletproof, but it's failing in this case: ...
78 views

### Plotting the Full width at half maximum as a function of a parameter

I have this function and I want to plot the FWHM of it as a function of the parameter "a", defined between 0 and 10. It should look like the picture attached. I also put the original equation in case ...
495 views

### Plot numerical solutions for a varying parameter

I would like to solve this equation $\log{\frac{a}{1 - a}} + b (1 - 2 a) = 0$ letting varying the parameter $b$ in $\lbrace 0,1,\ldots,20\rbrace$ and then plot the result. I am trying writing the ...
75 views

### Getting non-real answers when assuming variable is real when trying to numerically find maximum entropy distribution

I'm trying to find the maximum entropy distribution as such: Assuming[Element[l, Reals], NSolve[Sum[Exp[l i] i/Sum[Exp[l j], {j, 0, 100}], {i, 0, 100}] == 50,l]] ...
2k views

332 views

### Creepy numerical artefacts of a closed-form solution

I'm wishing you a nice day and here is my problem: I tried to obtain relation between chemical potential and temperature in a semiconductor and I arrived at this equation:  2 e^{-\Delta/kT} \left( ...
357 views

### Why does my function return an expression rather than a number? [closed]

I feel like I'm going insane. I have a function $f(x)=e^{-x^2}$ which I need to evaluate using forward, backward and central first order finite differences with intervals ...
513 views

### Matching pair of numbers {a,-a}, where a is numeric

Imagine you have a list of pairs of numbers, such as {{2,-2}, {1,5}, {1,-3},{-3,3}} The task is to reduce the given list to a list of pairs of type ...
107 views

### Determine whether one value is divisible by another [closed]

How do I determine whether one number is evenly divisible by another in the case of large numbers, for example: 52^52 / 52!
693 views

### Center column heading in TableForm

I have a TableForm as follows: ...
86 views

### Difference Eigenvector values in mathematica 9 and mathematica 10 [duplicate]

I have the following matrix; ...
136 views

### The problem (time) caused by ?NumericQ

In here, I asked a related (similar) question. Using ?NumericQ seems have slowed down the entire calculation. But I now have a more serious problem: ...
161 views

### Error with numerical summation - how to specify “n choose r”?

I'm trying to do the following sum: NSum[((50000 - x) choose x)*(1/3^15)^x*((3^15 - x)/3^15)^(50000 - x), {x, 1, 4}] But I keep getting an error saying: ...
3k views

### Could I define 0^0 to be 1? [duplicate]

Many occasions, where I need to work numerically with functions. For a variable strictly between 0 and 1, during the optimization, it could become 0.^0 or 0^0, which then become indeterminate. Is ...
157 views

### Speed up numerical optimization (for plotting and solving)?

Briefly speaking, I want to plot a function PIfun[], which its value is based on numerical optimization using NMaximize. It ...