# 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.

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### 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 returns ...
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### 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 ...
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### 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 ...
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### 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 ...
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### Using If statement to evaluate lists

I have a list of x,y values and i am finding the distance between each point, So for 20 point in my file I have something like this, ...
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### 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 ...
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### 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 ...
60 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 ...
284 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 ...
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### 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 (<...
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### 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 ...
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### How does mathematica decide what x_ is in MemberQ[list,x_/;(x==#)]&/@list

Consider the following code: list={1,2} MemberQ[list, x_ /; (x == #)] & /@ list This gives {True,True} ...
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### Using a Which statement with Graphics3D [duplicate]

*Problem solved in the comments I am trying to write a function that outputs a different graphic depending on the user's input, with four total options. I was making a test version and am running ...
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### 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 ...
38 views

### Aligning Conditional Controls in Manipulate

Consider the following code ...
104 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 ...
659 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}]; ...
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### 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 ...
220 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; ...
50 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 ...
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### 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 ...
324 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. ...
29 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][] == 0) :> 1}, {4, 4}] This should give a $4\times 4$ matrix in which the ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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: ...
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### How to include conditional statements in NIntegrate?

I have a function g which is the result of another integrated function f. This function (f) ...
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### 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] ...
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### 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 ...
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### 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 ...
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### Checking if an edge is an element of a list of edges

I have graph whose edge list is given by ...
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### 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 ...
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### 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]) ...
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### List, map function based on a condition

I have the following list: ...
60 views

### Combining With, If and SetDelayed

I just noticed that With[{x = 1}, If[x == 0, 0, 1]] returns 1 (as I expected) but ...