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Questions tagged [equation-solving]

763 questions
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How to accurately decompose positive semidefinite matrix and use the lower triangular part in linear equations

I have n arbitrary p x 1 vectors x_i, and p x k matrices A_i, and n p x p positive semidefinite matrices S_i, where some (often most) of the *S_i*'s are same (for example only two different S matrices, one positive definite which applies to…
Jouni Helske
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Independently solving for rows with mrdivide (B/A)?

When I answered this question, my answer started with: "For starters, you can get rid of all the if-statements by storing all the names in a cell." The "For starters" bit was because I thought that I could add an edit with a vectorized solution. But…
user1884905
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Java equation parsing for 1.2

For implementation specific reasons, I have to use Java 1.2. I am trying to parse a String object with only numbers (I replace variables beforehand to abstract that step) and operators (PEDMAS). I have found a lot of libraries that do this well, but…
Joel Gallant
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Matlab division of large matrices

Possible Duplicate: Efficient way to solve for X in AX=B in MATLAB when both A and B are big matrices I am trying to solve the equation Ax=b in matlab, by doing X=A\b. However the problem is that A is a huge matrix (2048000x2048000), and matlab…
stckjp
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Rescuing solutions from Maple's solve

I have something like solutions := solve ( {eqn1=0, eqn2=0, eqn3=0, eqn4=0, ... } ) which returns something like: solutions := {Ax = -.2312688085, Ay = -7.770329620, Bx = -19.76873119, ....} How can I access and save each solution? Is "Ax :=…
sports
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Solve an equation containing three unknown prime numbers

I was recently asked a question in an interview & have been unable to crack it, after my own efforts have failed & Google not showing any results , I am posting it here so that anyone else may also try their hand on it . Given the equation: a (a +…
user1460604
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Matlab generated C code does not work properly

I would like to solve an equation (A*x=b) with Matlab in my iOS app. I generated the C source files and added them to Xcode. The strange thing is that for the same (A,b), I get different results in Matlab and in Xcode. I use the default settings.…
János
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f(n), understanding the equation

I've been tasked with writing MIPS instruction code for the following formula: f(n) = 3 f(n-1) + 2 f(n-2) f(0) = 1 f(1) = 1 I'm having issues understanding what the formula actually means. From what I understand we are passing an int n to the…
melMPLS
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Solving 5 Linear Equations in Python

I've tried using matrices, and it has failed. I've looked at external modules and external programs, but none of it has worked. If someone could share some tips or code that would be helpful, thanks.
JShoe
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Using fsolve command in MATLAB

How can I solve these kind of equations? (-1.5/w)*sin(w*t) + 1.5*t - 0.45 = 0 Knowing that: w = sqrt(10) Thanks for your help.
user1359539
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Formulating the exponential equation given a certain pair of points

I have the following pairs of points: (0 , 100) ; (0.81 , 41) ; (1.38 , 20) ; (1.75 , 9) ; (2 , 4) How can I determine the equation of the curve passing through this points? Thanks very much! UPDATE What I'm trying to achieve is to get the function…
Bruno Morgado
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Maple is left ''evaluating'' when using the solve command on the following equation

I have used the code in the image, when compiling the entire sheet, it stays in "evaluating" for several hours. Is there a way to speed up the process or fix this problem? Maple code:…
DieGo
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Solve non linear system of equations with rootsolve

I'm trying to solve the following nonlinear system of equations with $sigma^2_2$ and $\mu_2$ unknown : And here is the code I used in R with the rootSolve library : library(rootSolve) mu_1 <- -2.931476 sigmasq_1 <- (1.084857)^2 mu_Z <-…
outofthegreen
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Python: Positive integral solutions for Linear Equation

I want to find all POSITIVE INTEGRAL solutions for a,b for this simple, toy linear equation: a + 2b = 5 and for which the solutions are: a|5|3|1| b|0|1|2| I've tried a few things after going some posts here and the "python-constraint" module was…
The August
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How to solve an equation that contains sigma sum to find the upper limit of sigma in Python

I want to find an integer value from a sigma contained equation with two variables like this post where x (a real decimal value) range is between two limits e.g. known_xmin_value <= x < known_xmax_value. 1 is the lower limit of k (which is the…
Ali_Sh
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