Hi All Maybe it’s a silly question for experienced users, but I’m rather new and I’m having troubles. I need to know if there is a way to force Mathematica to work in the Reals domain. For example, if I do Plot[x^(1/3),{x,-10,10}] I obtain a plot only for positive reals, For negative ones Math…

The basic mathematical issue is that the grand principles of algebra and analysis operate in the complex domain. Often, you have to reason through the complex domain to get a real answer. Any attempt to restrict Mathematica to operate in the real domain will generally impact its ability to break a p…

Yes, that is the answer. Thanks!

However, here you can download the obsolete add-on package which did the job I actually need. Works for version 6 Miscellaneous`RealOnly` Legacy Standard Add-On Package -- from Wolfram... This is the legacy standard add-on package Miscellaneous`RealOnly` from Version 5.2, with minimal …

Another way to look at it: for negative real numbers, there are several solutions coming from the complex roots. For instance, in the example above… in:= solutions = Solve[x^3 == -10, x] // N out:= {{x -> 1.07722 + 1.8658 I}, {x -> -2.15443}, {x -> 1.07722 - 1.8658 I}} These solutions all hav…

I am sure my reply is off topic, but I have puzzled over a similar issue of reals and imaginary solutions. In one problem, I have a messy integral whose integrand has no poles and is regular. Yet when I perform a numerical integration over some limits it will often throw off an imaginary solution. …

Luther, no, probably not an error on your part. Some integrals do not converge in the limit x → infinity. For instance, solutions for an oscillating system will cycle around a stable state (and have “imaginary” parts). Solutions for an oscillating system, driven at resonant frequency (without prop…

And thinking some more about Caitlin’s observation: Consider that -1 = Exp[Pi I], then an nth root of -1 is Exp[Pi I / n]. The n nth roots of unity are given by Exp[2 Pi I k / n] with k from 1 to n. (de Moivres numbers) Multiplying the nth root of -1 by these gives the n nth roots of -1 as Exp[(2…

The shortest path between two truths in the real domain passes through the complex domain. -Jacques Hadamard Luther, you’re probably not making a mistake. This kind of problem is inherent in mathematics. Integrate uses general methods to obtain an antiderivative of the given function. Those methods…

Thank you, David. I must give credit where credit is due, to Leonhard Euler! I was wondering whether someone might suggest a parametric plot for representing real and imaginary components. It is Pi Day after all! An alternate, continuous representation that includes the subset you’ve explored ab…

How to force Mathematica calculations in Reals domain only ?

Questions

thaikee84 (Thai Kee Gan) March 16, 2015, 3:09am 33

Hello guys, can you help me with my problem in this thread?

in that discussion, the formula is just an example of my work using ParametricNDSolveValue, the problem surfaced when FindRoot have an answer of complex value. is there anyway to force FindRoot to present only Real numbers?

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How to force Mathematica calculations in Reals domain only ?

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