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Questions tagged [equation-solving]

763 questions
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How to solve a symbolic system of equations in Matlab

I know it has to be a stupid error,but I really can't solve a system of this type: b = a2*cos(q1 + q2) + a1*cos(q1) a2*sin(q1 + q2) + a1*sin(q1) d1 + d4 + q3 >> solve(b,[q1,q2,q3,q4]) Warning: The solutions are parametrized by…
user1834153
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Optimizing the equality and inequality operators

I have some structures that are very expensive to compare. (They are actually trees with distinct branches.) Computing hash values for them is also expensive. I want to create a decorator for the eq operator that will cache some results to speed…
haael
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What is the fastest way to numerically solve a system of multivariate nonlinear equations with binary variables?

How do you solve a system of multivariate nonlinear equations that has three equations and 5000-20000 variables that can either be 0 or 1? The system probably has a lot of solutions, but I only need to find one of them. Thanks
Jessica
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Algorithm to solve an equation

I have this problem for the course "Algorithm and data structures" You have a equation x^2+s(x)+200·x=N, where x and N are natural numbers and S(x) is the sum of digits of number x. On the input we have N and A, B such that A≤B and A,…
Bojan Trajkovski
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C - function to return curved result

I have a general programming challenge for you all. I've been scratching my head trying to figure out the best way to do this... I'm working in C and I've got a "speed" value that is passed to my program. It ranges from 0-255. This speed value needs…
sscode
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Solving an equation in Python. Calculating nth digit

I need to write a program in python that given an integer as input calculates the digit in a continuous row of natural numbers starting by 1 and continuing to infinite(ex. 12345678910111213141516171819202122 etc...) So for example if we input 17 it…
buster
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Solving equation slow

I have an equation (5th order Polynomial) and I have to solve it every time for different variables A,B and Coeff as written down. And the coefficient are quite alot (100000) I had no other way than using the for loop to do it but it is incredibely…
Jack_111
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Analytical gradient for bisection method nested within objective function

I'm attempting to fit parameters to a data set using optim() in R. The objective function requires iterative root-solving for equation G so that the predicted values p brings the values for G (nested within the objective function) to 0 (or as close…
Eric
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Problems with multiplying lists in python

Consider a differential equation, do be precise, the Polanyi-Wigner equation: dy/dt = - v*(y(t))^n * exp(-E/(kt))/b (*) This equation describes the desorption behavior of particles from a surface. An experimental technique called thermal…
Phil Ipp
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Custom transfer function based on system matrix

Background: I have a complex mechanical oscillation system. With analogies I transformed it into an electrical circuit (every element is a RLC-oscillator). The only way to calculate the circuit is nodal analysis and it's too complex to do it by…
Robert Seifert
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Solving Equations with Python and Sympy and getting numerical answers

I'm trying to use sympy to solve equations, but I would like to get a straight numerical answer. My script is like this: from sympy import…
user2632453
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How to configure temporal / time linear programing constraints using PuLP?

I am trying to solve a hypothetical linear problem using PuLP. The problem aims at minimizing the costs of an operation over a 5 year horizon while maximizing product shape and condition. The problem must generate 5 costs, one for each year while…
dassouki
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symbolic system of non linear equation matlab

I'm trying to solve symbolically the following system of equation: Sys = [... k1*x - y == 0,... y - k2*z*w == 0,... 1 - x*k8 - y - w == 0,... k3*q + k5*q*r - k2*w*z - k4*z*t == 0,... 1 - z - q == 0,... k4*z*t - k5*r*q == 0,... …
Yyrkoon
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sensitivities using assimulo ida(from sundials)

I'm trying to solve a problem with sensibilities using ida with assimulo. solving the problem without sensibilities works fine but now i want to do it with sensibilities in finaltime, initial values and controls(parameters that are used in my…
Annah
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Quadratic functions in c

I have almost everything working except for solving for X in line 25 i keep getting an error saying " term does not evaluate to a function taking 1787 arguments" i had it giving me a 1 or a 0 but as i kept messing with it i lost where i was at and…
Pwoods
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