Questions tagged [conditional]
Questions about programming or mathematical constructs that enable verification, selection, or branching behavior when one or more criteria are determined to be True.
502
questions
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Make a list of the first 100 primes, keeping only ones whose last digit is less than 3
This is a question from an "Elementary Introduction to the Wolfram Language" Section 28: Tests and Conditionals. We are asked to "Make a list of the first 100 primes, keeping only ones ...
- 21
3
votes
1
answer
77
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Condition inside pure function
Why condition /; not work inside pure function?
Suppose we have:
...
- 859
3
votes
1
answer
100
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Compute the area of the union of the intersections of two conditions
I have four conditions over the two-dimensional domain $x,y\in[a,b]$. I want to use NIntegrate to compute the area of the union of the intersection of the two ...
- 327
0
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0
answers
40
views
Optimization of conditions applying
Let we have some data generator, e.g. lazy tuples or permutations.
I need to select data by some conditions cond1, cond2, …, up to 5-6 conditions.
All of them need ...
- 859
1
vote
2
answers
360
views
Parallelize a "For" cycle
I'm trying to parallelize a simple routine inside a "for" loop. Essentially, I need to compute the roots of a function $f(x)$ that depends on the discrete parameters $d$ and $R_0$. However, ...
- 491
1
vote
2
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57
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Weird behavior of Which with lists [closed]
To demonstrate my problem, let's create a little function:
...
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6
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1
answer
129
views
0
votes
3
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55
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Efficient and compact replacement for Association in the following case
Consider the following association:
...
- 4,866
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2
answers
74
views
How to minimize computational time in an if condition?
I have a code as below:
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3
votes
2
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297
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Why does Select not work here?
Why does this not work? It returns empty while I expect the first two elements are selected.
...
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6
votes
2
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142
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Generate all adjacency matrices of size $n=4$ s.t. $a_{ij}\neq a_{ij}$ and $a_{ii}==0$
I want to generate a list of adjacency matrices of size $n=4$ s.t.
The diagonal is zero: $a_{ii}=0$ for all $i\in\lbrace 1,2,...,n\rbrace$
There are no 2-cyles, i.e. if $a_{ij}==1$, then $a_{ji}==0$ ...
- 91
4
votes
2
answers
116
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How to discard the repeating elements of a list [closed]
Lets say there is a random list of expressions :
a={Sin[x], Sin[3 x], Sin[4 x], Sin[x], Sin[4 x], Sin[x], Sin [5 x], Sin[3 x], Sin[5 x]}
Plot[{a}, {x, 0, 2 Pi}]
...
- 801
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0
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89
views
0
votes
2
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112
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Selecting the specific values from a table and saving in a table:
I have the following code:
...
- 801
0
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0
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43
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Preventing Evaluation of Body of Manipulate
Overall, I am looking for a way to prevent the evaluation of the body of Manipulate until the controls meet a certain condition.
For example, consider the following....
- 1,587
2
votes
0
answers
98
views
The fastest and most scalable way to write a nested loop
The problem is to find the weights {w1,w2,w3,w4} that satisfy the condition. Which is the fastest and most scalable way (e.g. for 10000 weights) to write this ...
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5
votes
5
answers
152
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How to select elements from a list of pairs based on first element belonging to a different list?
This is my very first question and I really appreciate this ability and thankful the community.
I have two lists and need to select only those pairs from the first list, first element of which is ...
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1
answer
93
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Is there any alternative for conditional plot that gives a more precise result in a shorter time?
I have the given function $Func$ and want to have a plot of those domains where $-3\leq Func\leq 3$ in precise details. I am using ...
- 361
0
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1
answer
68
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How to plot multiple functions with conditions that assign values of some of them to be greater than the others?
i am trying to plot multiple functions in mathematica but i would like to do this in such a way that the values of two of my functions are always greater than the other two.
my functions are:
...
2
votes
2
answers
79
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How to speedup comparison in the following example?
I have the following problem: I would like to generate random values of some variable $z$ obeying some distribution, but simultaneously within the interval zmin<...
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4
votes
4
answers
181
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Creating a cycle with conditions
I would like to arrange a gift exchange between 5 people, Alice, Bob, Carl, Danny, and Ellen, and I would like the gifts to be passed in a randomly created cycle (B->C->A->D->E->B), for ...
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0
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84
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Removing "spikes" in data
Imagine I have a data set which gives me the following ListLinePlot
Is it possible to define a function over the data set that removes the "spikes" ...
- 4,233
0
votes
1
answer
79
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Check the existence of roots based on parameters
I have a function which has one variable $r$ and two parameters $M,\lambda$. Whether or not the function has roots, depend on the parameters $M,\lambda$. I want to obtain a parameter space such that ...
- 83
0
votes
1
answer
81
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Remove conditional for ThreeJSymbol [closed]
When I evaluate:
Assuming[3 > jj >= 1 && jj \[Element] Integers,
ThreeJSymbol[{jj, 0}, {1, 0}, {2, 0}]]
it outputs an expression saying that if
$3 &...
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2
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73
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Is there an alternative way to obtain the given plot directly from the equation $f(a,b,x)=0$? [duplicate]
I have the equation $f(a,b,x)=0$ where the function $f(a,b,x)$ is as follows
f[a_, b_, x_] := (x^2 + 2) (Sin[5 a] + Sin[3 b]) - 3 (x^2 + 1) Sin[x]
I want to plot ...
- 1,159
7
votes
3
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360
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How to write a condition for FindMinimum correctly
I would like that, when finding the minimum, the FindMinimum analyzes the variables (x and y) each time and finds q, depending on the current values of x and y. Can I somehow write this condition into ...
- 1,393
2
votes
1
answer
110
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How to plot a function with different conditions (if or which or piecewise)
The given function is
This function is plotted to be
...
- 1,262
0
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1
answer
52
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Dynamic 2-state toggle button difficulty returning to original state
I had this working fine this morning, but I proceeded to refactor, and somehow I cannot get it to toggle like before. It does initialize, and it does go from state-1 to state-2 but not back to state-1....
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2
votes
1
answer
51
views
Contour plot within upper and lower bounds
I have a mathematical function $f(p,q)=10^{-10}\frac{p^4}{q^2}$. I want to make a contour plot within the region where $10^{-3}<f(p,q)<10^{+3}$. I have tried the following three codes (one is ...
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1
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69
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2
votes
1
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292
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What's wrong with or? [closed]
Consider
Clear[x];
x = 2;
x < 2.9 || x > 3.1
This yields
True
So, everything is o. k. (interesting)
But when you replace ...
- 123
0
votes
4
answers
110
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Solve conditional term with mathematica [duplicate]
Solve mathematical conditional expressions with Mathematica, e.g if $x+y=3$ and $xy=-1$ , what is result $\frac{x^3+y^3}{x^2+y^2}$
0
votes
1
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60
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Expectation function vs Integral function
I am having trouble understanding how Mathematica computes a conditional expectation.
Consider random variables $v\sim N(0,\tau_v^{-1})$, $s_0=v+\epsilon_0$, $s_1=v+\eta+\epsilon_1$, where $\epsilon_0\...
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1
vote
1
answer
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Table mix with If function [closed]
Anyone could explain to me which problem is? after running the function "Table" combining with "If" as below, but the result is not a value instead.
...
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4
votes
2
answers
117
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Unexpected behaviour of Condition with Cases/MatchQ?
When using the unsorted version of Complement in this question I met the following unexpected result,
...
- 1,693
5
votes
2
answers
835
views
How to generate a list of random numbers with conditional statements
I want to generate a list of numbers with certain conditions.
Eg.
First I generated 10 random numbers between 1 and 20.
M1= RandomReal[{1,20},10]
Now I want to ...
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1
answer
93
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1
vote
1
answer
122
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0
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Plotting a conditional expression
I'm trying to plot the feasible region of a maximization problem with PlotRegion3D. This region is the intersection of two constraints and I'd like to plot also the ...
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4
votes
4
answers
213
views
Modify list elements if last two entries are equal
Suppose I have a list as follows
{{1, 1, 1, 1, 1, 3}, {1, 1, 3, 4, 1, 1}}
and I want to check the last two coordinates are equal or not. If that is the case then I ...
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3
votes
1
answer
76
views
Select with simplification does not work
Given a list, I want to find all elements that have positive imaginary part.
For example, if $y,z\in\mathbb R$ and $a>0$ and the list is $\{ ia+y, -ia+z\}$, then the result should be $\{ia+y\}$.
...
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0
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82
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Simplifying conditional expression
I have an expression of the form
ConditionalExpression[I a + y1, {True, True, True, True}]
as a result of some computation. (The expected answer is just ...
- 1,043
1
vote
1
answer
77
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How to use an "otherwise" clause in `Which`
I want to classify a set of vectors according to the number and position of zeroes they contain. The components of the vectors are non-negative. I'm using
...
- 563
1
vote
2
answers
112
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Conditional mathematical expression [closed]
I want to produce A, B, C, D and E values between 0 and 2*pi with two conditions:
`A!=B!=C!=D!=E`
And
(C,D,E)!=n*pi/2
n is an ...
- 1,262
1
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2
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92
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2
votes
2
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99
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How to find that this be always real number
I don't know how to find out this is be real number for l[y]?
...
- 447
0
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1
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89
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If or Piecewise dependent coefficients in NDSolveValue
This:
but the following (placing the partials inside the If) does not. Any suggestions?
5
votes
1
answer
215
views
Creating a list of conditions
I am trying to create a list of conditions using Table[] in the following way:
...
- 1,147
2
votes
1
answer
81
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How to find conditional probabilities for simple 4 categories problem?
Imagine you are give the following problem:
There is a 50% chance of diagnosing an illness correctly as "Known" instead of "Unknown".
There is a 50% that available treatments &...
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InputField : only integer or list of integers in a specific range
I'm making a dynamic structure which reads some output from a FEM program (node results).
I'd like an inputfield in which I specify the number(s) of the nodes I am interested in. The value of the ...
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