# All Questions

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### Diagonal minors of matrix

I need to calculate the minor of a matrix. I am going to use Mathematica example here, In[1]:= (mat = Table[i^2 + i j + j^3, {i, 4}, {j, 4}]) // MatrixForm; Minors[mat, 3, Identity] // MatrixForm; ...
13 views

### How use part on a simple matrix to extract individual elements, not rows or columns [duplicate]

I am mystified by how the function Part works given that I have tried many times to extract simple elements of a matrix. My matrix is ...
5 views

### module function giving Null values for the following code(Stiffness Matrix Problem): [on hold]

The module function giving Null values for the following code(Stiffness Matrix Problem): ...
18 views

### Deleting rows and columns to get submatrices? [duplicate]

I did not think that this would be difficult to find but how do I drop rows and columns from a full matrix? For example, I would like to delete the last row and first column but have trouble making ...
66 views

11 views

### How to converrt RGB to YCbCr [duplicate]

While converting rgb to Ycbcr, do we get values as floating point numbers? I would like to have Y, Cb, Cr values as integers. Is it possible?
24 views

### How to define a function [on hold]

How can I define a function which depends on a function of x? Something like this f[u[x]_,u[x]']= u[x]' + a [x] u[x] +b[x]
17 views

### Elements inside arrays seem to be strings rather than signed numbers, at least Mtmca doesn't treat them as signed

When I have code like b = Array[Subscript[be, #] &, {3, 1}] b = b /. {Subscript[be, k_] :> Subscript[-be, k] /; k>1} I am noticing that Mathematica ...
26 views

### Mathematica refuses to evaluate this expression symbolically while a very similar one works [duplicate]

Suppose I have the following code ...
73 views

### Replace elements in matrix to make it symmetric using automated procedure

I am generating a matrix using (mat2 = Array[Subscript[a, ##] &, {4, 4}]) // MatrixForm but would like to force Mathematica to make it symmetric. Thereby I ...
68 views

### Strange behavior when setting NumericQ of a symbol

It happens both in v9&v10. If you try this a^0 a^0 (1/a)^(3/2) a^0 (1/a)^(5/2) Mathematica returns 1 (1/a)^(3/2) (1/a)^(5/2) It's trivial. ...
57 views

### Issues with Arrow and Graphics3D [on hold]

I'm trying to plot a simple picture: a plane with a circle in it, and three vectors in the curve. Mathematica keeps saying that the array "has the wrong dimensions for a graphics coordinate list" and ...
43 views

### Nothing showing up on complex contour plot [on hold]

I am trying to graph the following function, where z:=x+y*I z(Conjugate[z]+2)=3. But with my code nothing is showing up. I've tried many different scales so something must be wrong with the actual ...
51 views

### Bug with password locked: Encode -> Import -> StringToStream -> Get

Let's save a definition. Encode it with password/key and Get it again. We will not use Get ...
70 views

### Adding Trace produces error messages

This is very strange. As I was trying to debug this problem, I noticed when I add Trace then I get lots of internal errors generated. This also happens the first ...
40 views

### How can I round a number up with two decimals? [on hold]

My problem is, that I have to round a number with many decimals to a number with two decimals. For example: The number is 3.467. Now I want to get 3.46. I tried it with Round[3.4647,0.01], but I only ...
49 views

### Problem with Simplify, Sqrt, and Set: What's going on?

I am having some trouble getting Mathematica to simplify an expression of the form Sqrt[x]*Sqrt[1/x], where x>0. The problem is that x is assigned to some complicated form by the time Mathematica ...
65 views

### Plotting Complex Numbers - Functions of Complex Numbers [duplicate]

So I have to generate a few different plots with z, where z is a complete number... z[x_, y_] := x + y*I F[z_] := (25*Pi*z*I)/(1 + 10*Pi*z*I) First, I need to ...
67 views

### How to find and verify relationships between functions?

MMa gave me a complicated result involving Hypergeometric0F1's. It was much less complicated after I discovered this identity: ...
19 views

### Size of the box using Manipulate function

I am using the following command: Manipulate[Graphics[Arrow[{{0, 0}, {a Cos[ω t], a Sin[ω t]}}]], {t, 0, 10, 0.1}] In order to display a vector in circular ...
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85 views

### How to find soccer balls in an image?

I have 10k images and I need automatically remove only soccer balls, excluding other types (volleyballs, baseballs, etc...). I'd like to use computer vision methods of V10 to find their masks and ...
64 views

Just bought a copy of E. J. Mcinnerney's textbook Computational Explorations in Magnetron Sputtering. However, when I download and try Chap2.nb from: ...
39 views

### Graphing a vector [duplicate]

I have a vector (in physic) designated asF1=250cos(60)i+250cos(60)j+250cos(45)k, and i would like to see it in a 3D graphic with the axis centered at the origin, after what i would include other ...
40 views

### Increasing CPU usage on Mathematica on a Product [on hold]

I hope someone can help me: I tried Parallelize, ParallelTry and others with AbsoluteTiming, and in every case the time was the same: what I have to do to calculate a Product in mathematica using all ...
35 views

### combining separate data into pairs after reading from excel so I can run regression

I have the following code that reads data from an excel spreadsheet: ...
56 views

### Combining MapAt and MapIndexed

The very last example in the documentation for MapAt is: MapAt applies f repeatedly if a part is mentioned repeatedly: ...
51 views

### How to plot and visualize a single linear vector in 3D? [on hold]

I have a vector (in physic) designated as F1=250cos(60)i+250cos(60)j+250cos(45)k, and i would like to see it in a 3D graphic with the axis centered at the origin, after what i would include other ...
61 views

### Function equal to Ctrl+Shift+I

No, it's not InputForm. Consider this example: ...
39 views

### Usb-harddisk and raspberry

Mathematica on raspberry. External media access. I have a usb harddisk, which is recognized by the system, but apparently not known to Mathematica. The disk is not seen when I try to open files from ...
43 views

### Mysterious message posted when I move the cursor in a custom function

I wrote a function called CPlot for complex plotting which is supposed to act a lot like Plot in its input format, but ever ...
161 views

### Function to calculate average of multiple lists

I have several lists of experimental data f[x] with different intervals Δx including some noise. ...
57 views

### Apply function on 2d array [on hold]

I have a function taking three variables as arguments. I would like to apply it to several random values. So I first created a table of 3 by 10 random values using: ...
50 views

FrontEndExecute[FrontEndToken["EvaluatorAbort"]] is equivalent of the menu item: Evaluation >> Abort. It works with ...
39 views

### How to properly pass function as argument here? --> NMinimize & NIntegrate involved

I had a problem of a similar kind here which was solved. Now after changing a few things in my problem setting I am suffering from the following problem. Let me first introduce methods/functions that ...
51 views

### Dynamic visualization of two histograms

I have two histograms histo1 and histo2: ...
82 views

### Force Mathematica to return numerical answer to (relatively) complicated differential function

I am trying to take the Laplacian of the LogDet of a 2x2 matrix that I call V\[ConjugateTranspose].V, and actually get a number out at the end. Why does Mathematica ...
55 views

### Low CPU usage. How to increase it? Should I?

I'm running a programme, and below are some graphics from the resources monitor from windows 8, while running my programme in version 9 of mathematica. Sorry for the foreign writings in the pics, but ...
32 views

### Find minimum summation and constraint values [on hold]

how can I get mi value to minimize this equation..?
53 views

### Equivalent parametric plots don't look the same

ParametricPlot[ {1, Tan[t]}, {t, -Pi/3, Pi/3}] ParametricPlot[ Sec[t] {Cos[t], Sin[t]}, {t, -Pi/3, Pi/3}] The second parametrization does not plot like the first, ...
49 views

### How to extract data points from an image of a log log plot? [duplicate]

I have a picture of a log-log plot, taken from a paper and I want to extract the data points so I will be able to plot them again along with results of my own solution. I would appreciate your help. ...
35 views

### What is wrong with my following vector plot

I am trying to plot the following: ...
27 views

### Force ReplaceAll to output vector of same length

I would like to do a replace in an expression... a = t; b = 1; a/.t->Range[1,5] (*returns: {1,2,3,4,5} *) b/.t->Range[1,5] (*returns: 1 *) but I ...
393 views

### Something interesting about Pi, but something seems amiss

I saw something interesting about text-analysis - bigrams - in Basic Text Analysis in Mathematica I wondered how the bigrams of Pi's digits might appear. As expected, take enough terms and every ...