# All Questions

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### How can I extract a list of terms with functions in terms of a specific variable

I have an expression in the following form: a f[x] + b Exp[g[x, y]] + r[z] f[y] + f[y] Sin[h[x, y, z]^2] + r[z] Log[t[z, y]] I want to extract an expression ...
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### Is there a way to make SparseArray distinguish between background values of different precision that are numerically equal?

To illustrate what I mean, consider the following: SparseArray[{{1} -> 1, {5} -> 1.}, Automatic, 0] // Normal {1, 0, 0, 0, 1.} As you can see, the ...
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### Find the area enclosed by the x = t^2 − 2t, y = √ t and the y axis [closed]

How do I find the area for these parametric equations : x=t^2-2t y=sqrt(t) and y axis Please help
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### Why can't mma be drawn in continuous form with the Fibonacci number general formula? [closed]

Of course, I know I can use Plot and DiscretePlot plot the built-in Fibonacci[x], but why ...
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### Why is RegionPlot@ImplicitRegion taking so long to compute?

I have an equation as a function of $a$ and $\theta$ and would like to visualise the intersection between this graph and a flat plane at a height of 1 unit. I tried using the ...
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### Evaluate, NDSolve and ReplaceAll do not work with tables of solutions

Why does the following report an error even though it returns a (seemingly valid) result? It's also weird that it returns a list of lists, whereas I would expect just a list. ...
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### Blank plot with numeric data

I seem to be getting a blank plot even though the data provided is clearly numeric and plots fine with other data. I just don't see what is special about this data that results in a blank plot. ...
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### Is there any way to refactor this equation?

I have a function produce this equation: (-4*dt^2*(c3 + a3*t)^2*t0^4 + dxC^2*(t0^2 + t1^2)^2 + dxM^2*(t0^2 + t1^2)^2 + dxY^2*(t0^2 + t1^2)^2)/(4*t0^4) Is there any ...
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### Defining a function recursively

I want to construct polynomials (or just function) $f_n$ from $f_{n-1}$ using mathematica. For some kind of reason, I didn't manage to do this. So basically something like a recurrence table, but for ...
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### A very basic question about weighted data

I have a dataset in the form {{A1,B1,C1,...},{A2,B2,C2,...},...} and the weights in the form {w1,w2,w3,...} Having this ...
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### DSolve and Plot [closed]

I was working on this equation to solve and plot it, but I'm little bit confuse?! ...
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### How to generate random points with weight distribution and specific criteria? [duplicate]

Consider some function $f(E_{1},E_{2})$, say $$\tag 1 f(E_{1},E_{2}) = \exp[-E_{1}^{3}+E_{2}^{2}]$$ I want to generate random $n$ points $E_{1}$, $E_{2}$ using this function as weights, with an ...
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### Code in Mathematica is not running [closed]

I have a question regarding my code in Mathematica. In the beginning when I tried to run my code it worked but then after I closed it and come back to do the same code but with different number it did ...
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### DensityPlot3D with clear division negative/positive value but also value dependent

It is easy to obtain a clear positive/negative boundary, with, exemplary ColorFunction -> Function[{f}, If[f > 0, Red, Blue]] Do you have an idea how I can ...
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### ContourPlot3D with variables within a ball [closed]

My attempt is (Mathematica 12.0) ...
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### Is it intended that CoefficientRules permutes exponent vectors when given a monomial order?

I noticed an odd behavior in CoefficientRules when you give it a monomial order: ...
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### How to use NDsolve for 2D PDE?

I want to solve the following 2D-PDE using NDsolve and plot it, I did: ...
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### Producing a random Wang Tile tiling image more efficiently

I'm following along with this SIGGRAPH 2006 paper Recursive Wang Tiles for Real-Time Blue Noise - there's a video here too. Eventually I want to try to produce the blue noise results in the paper, and ...
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### Problems with TagSet

I am new with TagSet and TagSetDelayed and I'm not understanding properly how they works. I introduced the following definition: ...
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### Why the animation of a function gives different results from the integral?

My function is: A1[B_, x_, t_] := (AiryAi[B*(x - (B^3*t^2)/4)])^2 (B is a constant) and if I use "Manipulate" : ...
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### How to extract Table data using regular expressions?

For example, the Table have follows structure: ...
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### Why does changing this code in a Compile make it work?

This is a follow up question to this one. In that question I asked why the following code didn't work: ...
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### Import website "Source" slows down after a few iterations

I am using Import[link, "Source"] to import the source of several hundreds of thousands of webpages in a while loop to process them. Each iteration has ...