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.
504
questions
3
votes
1
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248
views
How can I use WhenEvent with multiple conditions inside NDSolve?
I would like to use WhenEvent but I'm not getting what I want: I set the initial condition var\epsilon=0;
I want var\epsilon to change continuously over time, from to 0.1 if s'[t]>=0 or to -0.1 if s'[...
- 41
1
vote
2
answers
143
views
How do I loop my "If" statement?
I have list given by:
d=
{{{1,2},{1,1},{2,3}},
{{1,4},{3,3},{2,1}},
{{1,1},{3,1},{3,3}}}
Each row in the list is a different generation of the ...
- 433
1
vote
0
answers
41
views
Meaning of a condition $\left(\Re\left(m^2\right)\geq 0\lor m^2\notin \mathbb{R}\right)$ [closed]
I'm new to using Mathematica. I asked Mathematica to perform the following integration,
...
- 111
3
votes
3
answers
372
views
count conditional items in list
I have a list of the form:
{1,1, (1 if x>y, -1 if y>=x), -1}
I want to count the number of 1's in the list. The output I'm looking for is something of the ...
- 343
0
votes
0
answers
63
views
Integrals with conditional result
I am trying to get Mathematica to evaluate integrals such as the well-known Fourier orthogonality relations
$\int_0^L \sin \frac{2 m \pi x}{L} \sin\frac{2 n \pi x}{L}\,\mathrm{d}x=\begin{cases}0& ...
- 101
3
votes
2
answers
214
views
How to keep Switch default case as original function?
For example of below Switch function.
In[]:= Module[{f},
f[x_] := Switch[x, 1, 2, 3, 4];
{f[1], f[3], f[x]}
]
Out[]= {2, 4, Switch[x,
1, 2,
3, 4]}
...
- 589
3
votes
2
answers
102
views
Conditional statement in function
It seems the equality condition does not work as expected.
...
- 496
2
votes
2
answers
112
views
Vanishing function and Manipulate
Within Manipulate, I want to vanish certain controls if other controls satisfy a specific condition. The simplest case is to consider two checkboxes, ...
- 4,233
0
votes
1
answer
147
views
Is using an If[] condition faster than KronckerDelta[]?
I have a code which has a term in a summation like:
KroneckerDelta[M,0]*func[M]
where func[M] is a time consuming numerical ...
- 75
1
vote
1
answer
59
views
2
votes
3
answers
246
views
Specifying condition with NIntegrate
I have an integral
$$
P_{\frac12 + \mathrm i\mu}(\eta) = \frac{\sqrt{2}}{\pi} \cosh(\pi\mu) \int_{0}^{\infty} \frac{\cos(\mu\tau)}{\sqrt{\cosh\tau + \eta}} \mathrm d\tau, \quad \eta \geq 1, \quad \mu ...
- 372
4
votes
1
answer
196
views
Why does D ignore conditions specified on a custom function?
I define a function with a condition like so.
ClearAll[foo];
foo[expr_] /; FreeQ[expr, bar] := expr
Such that foo[12] returns ...
- 185
5
votes
3
answers
229
views
Among the first 10,000 multiples of 17
Hello I'm new with Mathematica and I can't find a way where I can do this condition.
Among the first 10,000 multiples of 17 how many have the sum of their digit multiple of 17?
The part for the ...
- 287
1
vote
0
answers
38
views
Are the conditions in ConditionalExpression necessary or sufficient?
I computed a limit and obtained it in the form of a ConditionalExpression (see below). Substituting the variables with numerical values in the resulting formula ...
- 121
1
vote
0
answers
130
views
What does a single vertical bar mean in ConditionalExpression? [closed]
I got the condition below as part of a ConditionalExpression. Those single vertical bars before and after $\frac{1}{k1}$ appear to be an absolute value but I don't ...
- 121
1
vote
1
answer
162
views
Defining a conditional statement for a function
I am trying to define a function that is zero when it is evaluated on real numbers and on a preset list of symbols. I am doing this by using
...
4
votes
1
answer
107
views
Use Lookup on associations that contain conditional statements
I am using conditional statements in a list of rules to replace values in a vector of data. Since the same operation can be performed faster using Lookup on associations I would like to use this ...
- 41
1
vote
1
answer
3k
views
Multiple conditions in If function
I wrote a function which returns 1 if x^2 + y^2<=1:
f[x_, y_] := If[x^2 + y^2 <= 1, 1]
Now I'm trying to continue this function to take in multiple ...
- 155
5
votes
4
answers
330
views
Recursive function, if and which statements
I am given this question: Let a function $ T_n(x) $ be defined by:
$$
T_{n+1}(x) = \frac{1}{x} T_{n-1}(x) - \frac{2}{7} T_n(x),
$$
where $ T_0(x) = 1, T_1(x) = x $.
I need to construct a recursive ...
- 199
1
vote
1
answer
54
views
2
votes
2
answers
124
views
Automate table to display figures
With reference to the post Automate Poisson Football Scores Prediction, I succeded in defining the Poisson probability density function for home (μh=A) and away (<...
- 401
2
votes
1
answer
151
views
How to use conditional clause inside NDSolve
I am trying to solve a differential equation that changes its behaviour depending on the value of the dependent variable. I've tried as shown below, but the computer does not understand my If clause ...
3
votes
3
answers
192
views
Is there a way to speed up the following calculation Table[If[TrueQ[],k,Nothing],{k,10^5,10^7}]
I've the following code:
Table[If[TrueQ[2+3^k>2^k+(-1+2^k)*Floor[(3/2)^k]],k,Nothing],{k,10^5,10^7}]
Is there a way to speed the calculation up in Mathematica ...
- 1,941
2
votes
1
answer
65
views
16
votes
0
answers
197
views
Reduce[Sin[x]==0,x] splitting odd and even multiples of Pi
as from Title, I'm wondering why Mathematica does not automatically give a single, simple solution for the problem
Reduce[Sin[x] == 0, x]
for which I obtain the ...
- 221
5
votes
2
answers
684
views
How to optimize the following function?
Consider the following function:
function[x_, y_] = If[x < Exp[y], Sqrt[1 - x/Exp[y]], 0];
functionTotal1[x_] = Sum[function[x, 0.02*j], {j, 0, 4*10^5, 1}];
...
- 4,866
1
vote
1
answer
72
views
Identifying transitions in an array
I have two arrays of elements. The second array is generated by the transfer of one or more element to another position. I want to know which element is transferred to which position. Following is the ...
- 1,103
7
votes
2
answers
322
views
Randomly generated coordinates
I want to code that will do the following:
Write a Mathematica function called randomHop that takes as its argument a list containing two coordinates x and y; ...
- 71
1
vote
2
answers
59
views
How to choose model parameters using `Piecewise` function
The following code (developed by m_goldberg) works as expected. The model parameters can be selected by using Button, being ...
- 4,865
1
vote
1
answer
255
views
Conditionally returning a constant if function returns Undefined
Often times functions might return Undefined in Mathematica, e.g. when the Volume@RegionIntersection is called for 2 objects ...
user52181
5
votes
3
answers
333
views
How to kick out points that are specific to a function
I have a list of xi,yi points. I want to remove any points from the list where x^2+y^2<1. I probably have to write a for loop of some sorts, not sure how to begin.
...
- 173
3
votes
1
answer
84
views
Condition in SparseArray does not check the condition for some matrix elements
Consider the following MWE:
SparseArray[{{i_, j_} /; (IntegerDigits[i - 1, 2, 2][[1]] == 0) :> 1}, {4, 4}]
This should give a $4\times 4$ matrix in which the ...
- 7,513
3
votes
1
answer
98
views
Changing ContourStyle based on an inequality
I would like to create a bifurcation diagram with ContourPlot. Suppose I want to plot the contour 1-2*a*Q+3*Q^3==0 with ...
- 957
2
votes
1
answer
383
views
Conditional expectation
Suppose I have a bivariate normal random vector $(Y,Z)'$ where $Y\sim N(μ1,\sigma_1^2)$, $Z\sim N(μ2,\sigma_2^2)$, and $Cov[Y,Z]=\sigma_{12}$. If I want Mathematica to compute the conditional ...
- 123
1
vote
1
answer
51
views
How do I get my function to output only true case for conditions on its arguments
I am quite new to Mathematica and have an issue regarding which statement.
cut[x_, y_] := which[x>y, doFunctionX[], y>x, doFunctionY[]]
cut/@{X,Y}]
I wish ...
0
votes
3
answers
80
views
How to find the root of g[x_] using If?
How can get roots only saved in the list?
Input
g[x_] := x^2 + x - 6;
g /@ Table[i, {i, -10, 10}]
If[g[x] == 0, i, Nothing]
Output
{-3,2}
How can I achieved ...
- 1,621
0
votes
0
answers
38
views
Mathematica Function Taxicab Numbers [duplicate]
I have spent days trying to compile this code and I cannot generate a list of taxicab numbers for the Hardy-Ramanujan Theory. Here is the module I wrote earlier:
...
4
votes
1
answer
249
views
How to include conditional statements in NIntegrate?
I have a function g which is the result of another integrated function f. This function (f) ...
- 1,451
0
votes
1
answer
55
views
Getting unexpected results form If expressions [closed]
I'm mystified by this:
g[a_, b_, c_] :=
Module[{d},
d = If[(b < 1), b, b + 1];
If[a < b, d = 0.];
d*c]
g[a, 20, 40]
...
- 63
2
votes
0
answers
146
views
Is Mathematica computing the conditional expectation correctly?
Given a simple case of say 2 independent trials each with probability of success 1/3. Consider a random variable that is gives the 3 times the total successes.
We can define this random variable in ...
- 8,779
3
votes
1
answer
99
views
Conditional formatting of `Table` with `Join` and `Transpose`
A simple example of what I'm trying to do (but I want to be able to apply the same principle to much larger data sets and with more complicated functions for low ...
- 2,077
1
vote
2
answers
132
views
1
vote
1
answer
146
views
Checking if an edge is an element of a list of edges
I have graph whose edge list is given by
...
- 165
1
vote
2
answers
69
views
How do I modify my code to detect cycles in this Collatz-like recursion?
A popular variant of the Collatz recursion is the following. Given a positive integer $n_i$,
If $n_i$ is even, $n_{i+1}=n/2$,
If $n_i$ is odd, $n_{n+1}=3n-1$.
The Mathematica code I'm using to ...
- 957
2
votes
3
answers
117
views
Highlight largest value in each column of `Table // TableForm`
I am exploring colossally abundant numbers; in particular the set of specific 'critical epsilon values'. I table the function DivisorSigma[1, n]/n^(1 + \[Epsilon]) ...
- 2,077
5
votes
4
answers
721
views
3
votes
1
answer
70
views
Combining `With`, `If` and SetDelayed
I just noticed that
With[{x = 1}, If[x == 0, 0, 1]]
returns 1 (as I expected) but
...
- 4,312
0
votes
0
answers
39
views
Why does NumberForm disturb the output of Rationalize? [duplicate]
I am currently using Rationalize after NumberForm in order to check if the some values of my function are in the ...
- 957
5
votes
3
answers
640
views
Arrange a list in ascending order by deleting list elements
I am new to mathematica and currently learning it by solving some basic problems.
I am trying to arrange a list in ascending order using a detailed IF loop. For instance if we start out with $\{1,65,...
- 95
2
votes
1
answer
81
views
Compare values in specific times between several days
I have imported csv file which is a Daily Load Diagram consisting of 3 months (1st dec 2018 to 28th feb 2019) and the values of current are taken every 10 seconds.
...
- 185