Questions tagged [piecewise]

Questions about the Piecewise function, which is represented by different expressions for different ranges of values of its independent variable.

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1answer
313 views

Sum of two Piecewise functions give wrong vector

I would like to calculate the normal at a certain point of a parabola. The parabola is defined only on a certain area according to a Piecewise function. Afterwards ...
10
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2answers
945 views

Solving a discontinuous differential-algebraic equation system for plasticity behaviour

I need to solve a discontinuous equation which is typical in theory of plasticity. For a simple case I get the following equation system (reformulated for numerical implementation): $s(t) = \frac{\...
2
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1answer
2k views

Piecewise smooth rectangle pulse

I am wondering how to create a single rectangle pulse with nonlinear riding and falling edges on both sides. I don't know whether it is better to do it piecewise or to mathematically transform the ...
0
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1answer
90 views

Finding a solution when there are two piecewise functions at play

The goal is to mathematically figure out where is the point when the both of the diagrams are the same distance to the Y-axis. The solution to such a problem can be obtain quite easily by just ...
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0answers
316 views

Piecewise functions Integration with symbol

I want to integrate one piecewise functions as following, ...
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0answers
96 views

Transform NMinimze into LinearProgramming formulation

I have the following maximization problem that I currently try to solve with Minimize/NMinimize. Unfortunately, this kind of solution method takes really long for large systems of equations and ...
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1answer
1k views

Integrate over piecewise function defined using /;

f[x_] := x /; x<0 f[x_] := x^2 /; x>=0 Integrate[f[x],{x,-1,1}] The above does not work (Mathematica returns it unevaluated), but the below does. <...
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2answers
303 views

Integration over a (non-parametric) curve defined by indicator function

I want to integrate the real function myFun defined on a 2D plane over the line locus, defined as the solution of a set of ...
1
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1answer
385 views

Understanding a piecewise function generated by Mathematica

After some simplifications I was eventually get the following piecewise function. ...
22
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5answers
5k views

Extracting the function from InterpolatingFunction object

I've used Interpolation[] to generate an InterpolatingFunction object from a list of integers. ...
3
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1answer
190 views

(Very) ill-behaved Piecewise Plot

I am interested in defining a function (with arguments: a symbol for a variable and a list of 6 points) that represents a quadratic interpolating spline of the points. Here is my attempt ...
2
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1answer
126 views

Plotting a piecewise function with strange subdomains

I have a function, which analityc expression is $C=2*max[b-c,0]$(you can see the expressions of b and c down). Then I have to considerer $q_\pm=\frac{(1\pm \sqrt{ (1-C^2)})}{2}$ and then to plot $E_n=-...
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0answers
104 views

Data paste in piecewise table

How can I paste data copied from several lines into a piecewise table, without pasting it in a single cell?
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3answers
2k views

Piecewise Polynomial Interpolation

Given some data pairs $(x_i,y_i)$, with $i=0,...,m$, and a degree $r$, I wish to build a piecewise polynomial function to interpolate these data. That interpolation should be continuous, and, on every ...
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3answers
2k views

Can NDSolve handle discontinuous data?

Backslide introduced in 9.0, persisting through 11.0.1 It is possible to numerically solve a differential equation if not-smooth data are involved? For example the following instruction return the ...
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2answers
469 views

Plotting 3D piecewise function with distinct colors

I want to draw the following picture in Mathematica as shown below with distinct color for each section.
1
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1answer
70 views

PiecewiseExpand doesn't take all kind of assumptions

Running PiecewiseExpand[expr, assum] does not work with all kind of assumptions. For example, the following line will not split the expression with absolute values in the chambers, considering m1=m2. ...
2
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1answer
273 views

Piecewise conditions with a parametric PDE

I'm using ParametricNDsolve to check best fit of a model (function Eb1) with some data, and I have four free parameters I want to test. I can easily construct a Parametric solution between the two ...
2
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2answers
4k views

3D Plotting with Piecewise function

I'm trying to plot the following function: $f(x,y)= \left\{\begin{matrix} (x+y) & (x,y) \in T \\ (x+y)^2 & (x,y) \notin T \end{matrix}\right.$ where $T= \{ y\leq -x+1, x\geq 0, y\geq 0 ...
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0answers
425 views

Integration of UnitStep or HeavisideTheta

I am using Mathematica 9. If I evaluate Integrate[Piecewise[{{1 - r, r > 0 && r < R}}, 0], r] then I get ...
8
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2answers
665 views

How to plot this function?

I'd like to plot the function $f$ in this answer https://math.stackexchange.com/a/788818/66096 Let $h(x) = \begin{cases} e^{ -\frac{1}{1 - (1-2x)^2}} & \mbox{ for } 0<x < 1\\ 0 & \...
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1answer
117 views

Inaccuracy of Piecewise function? [duplicate]

I have the following issue and can't find a solution so far. ...
0
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1answer
138 views

Define function that goes from one point to another parametrically

I have two points p1 and p2, and I want to get the parametric equation of a linear function that passes through those, but ranging from one point to another. For example, if I have 2 points {0,0} and ...
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1answer
328 views

Definite Integral, Piecewise, Error

I am trying to evaluate the following: ...
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2answers
206 views

Mathematica: Extract the piece that contains x=0 from within a piecewise function

In mathematica, I have a piecewise function similar to: Piecewise[{ {x^2 + 2*x - 4, 0 <= x <= 1/4}, {0, true} }] I don't ...
8
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1answer
3k views

Fitting piecewise functions

I have several large data sets which follow the following pattern: A position is measured, a force is applied until a new equilibrium is found. I'd like to find a fit for the position, at least at the ...
2
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1answer
170 views

How to constrain the range of a plot of a function to satisfy an inequality?

Given the function f[x_] := x^2, how can I plot f[x] over the range where f[x] >= 10 and <...
1
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1answer
2k views

Manipulating a piecewise function

A while ago I posted a question regarding differential equations. It was supposed to model heat transfer. We've refined our model a bit (using numerical methods now). Our code now looks like this: <...
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2answers
1k views

Trying to solve a differential equation with a piecewise initial condition

I am trying to solve $$u_t=\frac{1}{4}u_{xx}$$ $-\infty<x<\infty,\: t>0$ With the initial condition $u(x,0)=\phi(x)$ where $$ \phi(x)= \left\{ \begin{array}{lr} 1 & |x|&...
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1answer
1k views

Nonlinear fit with piecewise functions

I have an ensemble of data points $(x_i,y_i)$ and I need to fit them according to $y=F(a,b,x)$ if $x \leq x_{ref}$ and $y=G(c,d,x)$ if $x \geq x_{ref}$. The parameters I need to adjust are then $a,b,c,...
0
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2answers
733 views

Defining Piecewise Functions in Modules

In short, my question is the same as my previous one except that everything is now wrapped up in a module. The relevant code I'm working with is: ...
4
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4answers
1k views

How to build a funcion that returns a piecewise function

I dont know how to go ahead with this The problem statement is "Make a piecewise linear function maker that accepts lists of points as input and has a piecewise linear function as the output". Lets ...
5
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1answer
255 views

Define customised distribution with discontinuous CDF

I have the following CDF: ...
3
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1answer
2k views

Defining Piecewise Functions [duplicate]

I'm having trouble defining piecewise functions. What I have so far is a function that outputs something in a suitable format for Piecewise: ...
5
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3answers
447 views

Creating a function with integral zeroes of the 0th, 1st, and 2nd derivatives

I would like to be able to randomly generate functions, each of which satisfies $f : [-10, 10] \rightarrow [-10, 10]$ All the zeroes, critical points, and inflection points have an integral $x$-...
6
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1answer
664 views

Using Boole to integrate over region

I have a complex and long piecewise function to integrate, so I have written a Mathematica script that cuts the whole range of integration, evaluates the integrand in each region and then integrates ...
2
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2answers
577 views

Add Piecewise functions expanding domains

I want to reproduce these plots for further development in Mathematica: To do so I defined the functions A and B as following ...
7
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1answer
2k views

Why does piecewise plot have a discontinuity when the function, first and second derivatives are equal?

There were some related questions to this one, but in this case we have the function value, the first derivative and the second derivative all equal (that was actually the problem I was solving). We ...
6
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2answers
594 views

Using units and piecewise functions in Integrate

For simple cases, Quantities appear to be handled well by Integrate: ...
32
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3answers
4k views

Plot a piecewise function with black and white disks marking discontinuities

Let's say I'd like to plot Sign[x + 0.5]: Plot[Sign[x + 0.5], {x, -1, 1}] Mathematica will give this: This plot does not ...
5
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3answers
785 views

Colors for multiple piecewise functions

I have the following $3$ piecewise functions, and I would like that f1, f2 and f3 have $3$ ...
4
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4answers
802 views

How to select a certain portion of a piecewise function?

For example, if I have Piecewise[{{x^2, x < 0}, {x, x > 0}}], how do I select only the function that is for x < 0? I ...
12
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2answers
1k views

Is there a way to symbolically invert a piecewise function

I have a piecewise function that is continuous and strictly monotonic, like this: f[t_] = Piecewise[{{t/4, t < 0}, {t/2, t < 3}, {3/2 + (t - 3)*3, True}}] ...
7
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1answer
229 views

Slow NIntegrate over complicated domains (sometimes)

This is no longer a problem with Mathematica 10.* where I can use regions to do the integrations Overview I have a very large matrix I need to calculate where each element requires the integration ...
5
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3answers
536 views

Transform Piecewise[] into sum of indicators

I'm interested in transforming a piecewise defined function into a sum of indicator functions, ultimately with the aim to be better able to integrate them. As an example I would like to transform the ...
4
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2answers
354 views

Compile error from If but not from Piecewise

Consider this: point={1.,2.}; f1 = Compile[{{t, _Real}}, Evaluate[Block[{a, b}, {a, b} = point; If[t > 0., a*b*Sin[t], 0.]]]]; f1[2.] CompiledFunction::...
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5answers
1k views

NIntegrate extremely piecewised functions

I often need to integrate extremely piecewised functions, like the following one (not extreme, but gives an idea): ...
8
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1answer
2k views

why mathematica outputs “True” sometimes in outputs that are conditional to mean “in all other cases”? [closed]

consider this simple Input: Probability[g <= m && m <= -g + 1, {m, g} \[Distributed] UniformDistribution[{{0, 1}, {0, gg}}]] which generates a ...
5
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1answer
396 views

Error messages from compiling the Piecewise function

The following works Compile[{{x, _Real}}, Piecewise[{{{0., 0.}, x > 5.}}, {1., 1.}]] but if I enter the Piecewise[...] in ...
8
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2answers
502 views

How to display the support $\mathrm{supp}(f)$ of a piecewise function $z = f(x,y)$?

I'm wondering how to display the support $\mathrm{supp}(f)$ of a piecewise surface $z = f(x,y)$. As an example, let's consider the following piecewise function (and plot it): ...