Tagged Questions

For questions on writing functions (pure or using Set/SetDelayed) for any purpose, including the features that may be incorporated in those functions, such as options, patterns and conditions.

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Number of digits for factorial of 12345678987654321

What is the number of digits (IntegerLength) of the factorial of 12 345 678 987 654 321? The number of zeros at the end of this factorial was calculated and it is huge: exactly 3 086 419 746 913 569 ...
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How to make my fuction return a step count

I am new to mathematica, and I have this 3d random walker program which runs with a fixed (given) amount of steps. What I want it to do is to run forever but stop when two walkers collide (aka have ...
856 views

Reverse Polish Notation

Is there a way to evaluate a string containing RPN in Mathematica? SE thinks this question is too short, so let me expand on it. Do you know of any function, that provides the following ...
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How to organize expression by symbols (like Collect), but apply different functions to each coefficient

I want to mimic the functionality of Collect[expr, {vars}, func], but with the following modification: The function f that is ...
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Multi-case function: many single-case delayed assignments; or one Which[]?

A function needs to cope with many different forms of input, such as different heads (Plus, Times, ...
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How to define a function that is Listable for some but not all arguments?

I want to define a function f[x,y] that is Listable for only the first argument, not the second. If we use ...
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Pattern condition involving multiple arguments to a function

I can define conditions on individual arguments to a function: f[a_List/;condition(a),b_List/;condition(b)]:=(...) I am wondering if there is a way of declaring ...
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How to calculate the pseudo-remainder and pseudo-quotient of two multivariate polynomials

I have fixed some code, but it always gives me errors. Can anybody tell me its right code? ...
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How to inject segments of code into functions defined by SetDelayed [duplicate]

I need to define a set of functions that are written in terms of common but lengthy expressions. To effect this, I want to inject abbreviations for such expressions into the RHS of ...
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Rescale large numerical factors in rational functions

Given a rational function $$f(x_1,x_2) = \dfrac{r_1 x_1^2 + r_2 x_2}{r_3 x_1 + r_4 x_2},$$ with $r_i$ arbitrary real or complex numbers, is there a built-in function to get Mathemtica to rewrite as ...
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How to make a function to analyse a sentence?

I have two lists: grammarNonterminal = {{VP,{V,NP}},{NP,{D,N}},{S,{NP,VP}}} sentence = {{D,"the"},{N,"man"},{V,"hit"},{D,"the"},{N,"table"}} I want to make a ...
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Bug introduced in 8 or earlier and fixed in 10.4.0 Bug isn't present in version 5.2 I don't think I quite understand how Except works. I want to define $f(a,b) ... 1answer 254 views What is the difference between defining a function and specifying the type of argument, versus applying a test to that argument? Say I want to create a function that evaluates differently based on what type of argument is given. I've found two ways of doing this, ... 1answer 30 views Solution of a function that is in a variable [duplicate] If I want to get the solution for a simple function, e.g. a^x, I can use: a = 2; Function[x, a^x][2] However, if I have the function in a variable, I can't get ... 2answers 44 views Deciding whether the return value of a function is defined based on its input [duplicate] I have been met with the following problem: I have defined the following: myFunc[e_Integer]; That means, if I call: ... 2answers 289 views More elegant function construction for blues loop Is there a more elegant way to do this: ... 1answer 89 views Evaluate Limit only if both directions(sides) are equal?Ex:$\lim _{x\to 0}\left(\frac{1}{x}\right)=DNE$I want the limit of a function to only evaluate if both the left and right hand side are equal. For example$\lim _{x\to 0}\left(\frac{1}{x}\right)$doesn't exist(two sided limit). However, the right ... 1answer 85 views High-order functions and interactive objects I have been developing Mathematica code to interpret LaTeX code, extract formulas and apply various Mathematica operations (e.g. Simplify, ... 1answer 88 views ClickPane and InputField entry in a Manipulate By clicking at a point on the slope field for an ode, a solution is plotted through that point. Additional clicks produce more plots; the plots are saved in graph ... 3answers 81 views TagSetDelayed on a function with a delayed value I'm trying to automatically optimize cases when the user evaluates Length[returnsList[x_]] to instead use returnsLength: ... 2answers 88 views Defining arbitary Derivatives of functions If I have two functions like these f[a_,b_] and g[a_,b_]. Lets say ... 1answer 95 views Using a table as a variable in a function I have a bunch of arrays and need to extract specific rows and columns of these that obey certain criteria. So for one table I'd do like this ... 1answer 39 views Please explain this pattern/Message related issue and help with finding workaround I attempted to clean up my code and also add messages to functions if they are called with wrong arguments. This introduced some error which I tracked down to the following: ... 2answers 85 views Function where variable is integration bound Lets say I have a function of the form:$f(T) = T^4 \int_0^{1/T} \frac{x^3 dx}{e^x-1}$This is an example of the situation I am describing not a unique problem. I want to define it as a numerical ... 1answer 46 views combine two definitions into one [closed] Suppose I have two definitions of a function such as ... 3answers 212 views Make own rule for multiplication I'm new to mathematica, so I still cannot use it properly. I want to do symbolic programming. My question is : is there any way to define our own multiplication. Suppose$a,b$are arbitrary ... 1answer 81 views Define recursive function over two indices I have$x_i=(i-1)/50$for$i=1,\ldots,51 $. Given a function$ f(x) = x^2 $, I want to find$y_i^k$given by \begin{eqnarray} y_i^1 &=& f(x_i) \\ y_i^{k+1} &=& ... 3answers 314 views How can I create currying functions using pure function syntax? For example how can I write In: pureFunctionSyntax[myF] /@ {7, 3} Out: {myF[7, Log[7]], myF[3, Log[3]]} 1answer 82 views InverseFunction: how can I extract the function inside? This is probably a trivial question. But I could not find an answer. Given the explicit expression for ft in te assignment ... 0answers 50 views Mapping over two indices with a condition How can I use Map over two indices with a condition? I am trying to calculate second derivative of an eigenvalue,$\lambda_i(x)$, of$n \times n$matrix$M(x)$... 1answer 92 views Why must I specify the Global context for a symbol in a private package? I have written two versions of the function below in a package. When I load the package and call the function, Why does the first version where the variable s has no explicit Context return the long ... 0answers 43 views Piecewise in 2D with quadrants as conditions I am trying to define a piecewise vector field. Can the condition be of the form I am using (i.e. a quadrant)? I can't also make Piecewise work with more than two ... 3answers 137 views List of functions to list of parameters I am working in a Dataset and I need to create a function for a ChartStyle option of a ... 2answers 79 views Assigning function values in a memoized recursive module I have a complicated recursive module which I have memoized. I realised that certain isomorphs of inputs to this function will give the same output. Therefore I decided to memoize all such ... 1answer 60 views Prevent expression from evaluation in function when using ToString  I defined function fhold Clear[fhold] SetAttributes[fhold, HoldAll] fhold[para_List] := ToString[para]; What I want is that ... 4answers 233 views Recursive piecewise integral relation with piecewise base case? How is this recursive formula $$f_{n+1}(z) = \int_0^1 f_{n}(z-y)\,{\rm d}y$$ implemented in Mathematica? The base case is $$f_1(z) = \begin{cases} 1 & 0\leq z\leq 1 \\ 0 & ... 1answer 116 views How to properly define this function of function I encountered real problem at first, and here is the toy example variable argument stored some expression that is generated from other parts of the program. I ... 0answers 68 views Automating game simulation, using previous results [closed] Based on this question on MSE, I would like to simulate a game whereby player 2 enters a number, so as to test the strategy. The basis for this is the factor game online here. ... 1answer 149 views Why there is only HoldFirst but no HoldSecond, HoldThird, …HoldN? I feel that this must be a duplicate. But I just can't find such a post. Mathematica has HoldFirst, HoldRest, ... 1answer 98 views How to get name of “named row” in Dataset for function applied to each row After some calculations and a GroupBy I have a Dataset that is structured like this. ... 1answer 214 views How to tame the wild MMA? MMA is a free country. But TOO free sometimes. Just as an example: Clear[a] a[x_] == a[y_] ^:= Round[x] == Round[y] {a[3] == a[3.01], a[3] == a[4]} is {True, ... 0answers 55 views Memoized function with function parameter [duplicate] I have some code that takes a function and uses the function to do some complicated computation. Thus, I wish to store this so I don't have to repeat this. Below, it is more simple than my real ... 1answer 133 views How to find period of a discrete sequence? For example, {1,2,3,4,5,6,7,8} has period 1, the base is {1} {1,2,4,5,7,8,10,11} has period 3, the base is {1,2} I ... 1answer 58 views Setting a One Dimensional Function Equal to a Constant over a Specific Range I am trying to take the output from NDSolve and create a variable equal to the solution except for a certain range of values. Here is the code I am trying to use ... 0answers 46 views Improving numerical stability of the Goldstein-Price Function Goldstein-Price Function is a two-dimensional test function for optimization, defined as$$f(y,z) = \left(\left(3 y^2+2 y (3 z-7)+z (3 z-14)+19\right) (y+z+1)^2+1\right) \times \left(\left(12 y^2-4 y ... 1answer 101 views How to write or extend operators like$*\!\!*\$

I'm stuck on trying to define simplification rules for NonCommutativeMultiply, much like ExpandNCM found in Documentation Center, under Applications. For example, I'd like ...
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Construct a function whose definition depends on the values of its arguments and evaluates a Section

I have defined a function that returns different output according to the values of the axes of an ellipsoidal. If none of the Which statement cases is satisfied then the function evaluates the ...
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Pollard's Rho algorithm

I'm working in Mathematica and I'm trying to implement the [Pollard's Rho Algorithm for the Discrete Logartihm Problem][1].