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.
515
questions
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Trouble implementing switching hybrid system with NDSolve
I'm trying to use NDSolve to simulate a hybrid nonlinear system that switches between different linear behaviors based on states and inputs (i.e. switching from one linear behavior to another) which ...
3
votes
1
answer
125
views
Pattern matching vs. condition in a function
I'm trying to learn stuff from pattern matching but I found sometimes pattern matching does not work as I expected. Could anyone explain why the below outputs are not same? Thank you.
And could anyone ...
- 31
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0
answers
31
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How to find clear solution for iterative problem by condition $<v_k ,v_n>=0$ If $k!=n$
I want to find x[n] by v[n] values without x[n] in solution by iterative below problem:
<...
- 83
0
votes
1
answer
69
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A simpler way of identifying which elements of Tuples[{0,1,2,3},6] multiply with each of my codewords to give zero?
So I have a list of codewords. The codewords have length 64, so there are 64 codewords in my code. My code is over an alphabet of 4 (the code can be thought of as having four elements $0,1,2,3$ and ...
- 481
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votes
1
answer
45
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Creating an If function for the probabilities of the classes of images after using NetTrain
So I have 3 Classes the model can output after veiwing an image, at the moment it has a 70% accuracy, however this is not an issue as the plan is unless it's 85%+ sure on the Probability of the class ...
4
votes
4
answers
156
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How to check if at least one ordering of the given row matches one of the rows of a table?
Consider some list of elements
...
- 4,681
2
votes
4
answers
215
views
How to check if the given row matches one of the rows of a table?
Consider some table
tabb = RandomInteger[{0, 4}, {5, 4}]
and a row
row = RandomInteger[{0, 4}, 4]
How to check if ...
- 4,681
1
vote
2
answers
95
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Can you recover the original vectors that, when summed together, achieved a particular criteria
I am wondering if it is possible to take the binary strings of length $3$ (tuples) whose sums have weight $2$ (i.e they have $2$ non-zero entries)(binary case, meaning they have two $1$'s entries) $$u ...
- 481
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0
answers
44
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Identify a condition among variables that satisfy an inequality
I have a symbolic function that produces the output
a = (1 - e - mu/n) Log[(1 - e - mu/n)/(1 - mu/n)] + (e + mu/n) Log[((e + mu/n) n)/mu]
If I substitute ...
- 424
4
votes
1
answer
272
views
Confused about If statement [closed]
I have this simple test code:
n1 = 0;
n2 = 0;
m = 0;
If[n1 == 0, n2 == 1]
which evaluates as False, as it should. However, if I do:
...
- 145
2
votes
3
answers
107
views
SetDelayed assignment not producing expected result when using ReplaceAll
In Mathematica, I am surprised that the following code does not do what I expect (what I expect is in comments after each evaluation). The problem seems to be due to the fact that when I define test ...
- 269
3
votes
1
answer
81
views
Adapt elements in the list, condition by condition
Could you give me some advice?
Suppose I have the following list.
box[1,1]={{4.4, {1,1}, {a}}, {1.5, {1,1}, {a}}, {10.8, {2,1}, {3a}}, {10, {1, 3}, {3a}}}
I want ...
- 406
1
vote
1
answer
55
views
Redundant cases from Sum
I am new to Mathematica. I would like to understand why Mathematica returns redundant cases, and whether it is possible to simplify them to the generic case $(n>1)$ that covers everything $(n\ge0)$....
- 111
3
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6
answers
685
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Make a list of the first 100 primes, keeping only ones whose last digit is less than 3 [closed]
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 ...
- 481
4
votes
1
answer
98
views
Condition inside pure function
Why condition /; not work inside pure function?
Suppose we have:
...
- 1,197
3
votes
1
answer
104
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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 ...
- 349
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0
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41
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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 ...
- 1,197
1
vote
2
answers
372
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
answers
58
views
Weird behavior of Which with lists [closed]
To demonstrate my problem, let's create a little function:
...
- 2,366
6
votes
1
answer
137
views
0
votes
3
answers
60
views
Efficient and compact replacement for Association in the following case
Consider the following association:
...
- 4,681
0
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2
answers
76
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How to minimize computational time in an if condition?
I have a code as below:
...
4
votes
2
answers
318
views
Why does Select not work here?
Why does this not work? It returns empty while I expect the first two elements are selected.
...
- 507
6
votes
2
answers
157
views
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
117
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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}]
...
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90
views
0
votes
2
answers
117
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Selecting the specific values from a table and saving in a table:
I have the following code:
...
- 811
0
votes
0
answers
47
views
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....
- 1,607
2
votes
0
answers
122
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 ...
- 35
6
votes
7
answers
263
views
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 ...
- 117
0
votes
1
answer
98
views
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
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1
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98
views
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
81
views
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<...
- 4,681
4
votes
4
answers
185
views
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 ...
- 792
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0
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120
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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" ...
- 4,179
0
votes
1
answer
105
views
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
views
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 &...
- 147
0
votes
2
answers
74
views
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
answers
372
views
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 ...
- 1,753
2
votes
1
answer
126
views
How to plot a function with different conditions (if or which or piecewise)
The given function is
This function is plotted to be
...
- 1,554
0
votes
1
answer
56
views
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....
- 2,407
2
votes
1
answer
54
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 ...
- 635
2
votes
1
answer
69
views
2
votes
1
answer
294
views
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 ...
- 193
0
votes
4
answers
112
views
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
answer
64
views
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\...
- 213
1
vote
1
answer
74
views
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.
...
- 163
4
votes
2
answers
121
views
Unexpected behaviour of Condition with Cases/MatchQ?
When using the unsorted version of Complement in this question I met the following unexpected result,
...
- 2,208
6
votes
2
answers
1k
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 ...
- 117
2
votes
1
answer
97
views
