Questions tagged [equation-solving]
763 questions
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Generating random SoLE with certain conditions
I have to write an algorithm (using NumPy) that creates:
random system of 4 linear equations with 4 variables and integer
coefficients
two column vectors b_1, b_2 with integer numbers such that:
1) The first one makes created system Ax = b_1…
Lev
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How can the user input an equation for the program to understand?
OK so I'm fairly new to c# in the big scheme of things. I have encountered one of the first things I'm not 100% sure on how to overcome. At the moment I have a program that asks the user to input a number. This is fine if the user inputs something…
TOASTED PIE
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Octave dsolve with some symbolic parameters
I want to solve the following equation with Octave:
syms y(t) k T T1 % k, T and T1 are constants.
eq1 = diff(y,t)-k*y+k*T == 0
cond=y(0)==T1
dsolve(eq1,cond)
but Octave runs it like this:
{
(sym)
k⋅t
y(t) = T + (-T +…
Hamtah
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Calculate stationary points in JS with math.js
I want to calculate the stationary points of a derivative in JavaScript with the external library math.js.
So if I have f(x) = x^2, the derivative is 2x and the stationary points can be calculated making 2x = 0 so x = 0 . But the function in math.js…
user9885084
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1 answer
Why is an empty list returned when solving for this linear system in Maxima?
I'm trying to solve a simple linear system in Maxima using solve like so:
/*Standard form*/
eq1 : x1 + 3*x2 + s1 = 6;
eq2 : 3*x1 + 2*x2 + s2 = 6;
base1 : solve([eq1,eq2],[s1,s2]);
This however returns an empty list and I don't know why. Any…
sesodesa
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Solve quadratic equations without individually specifying cofficients
I am trying to solve equations like:
3*(3x-12)/(x+3)-2*(2x+3)/(3x-1) = 5
This is the code that I use:
eqn1 = 3*(3*X-12)/(X+3)-2*(2*X+3)/(3*X-1) == 5;
sol = solve(eqn1, X);
xSol = sol.X
This is the error that I get:
Error using sym/subsref
Too many…
iKnowNothing
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1 answer
How to solve multi-variable simultaneous equations numerically with some variables known?
How to solve a pair of nonlinear equations using Python?
In this question a pair of nonlinear equations that each has two arguments were solved.
Now I have more than two equations, each has a number of arguments. The number of arguments is more than…
Zhidong Li
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1 answer
Matrix data in Python Sub & Upper Diagonals
I have a file with a matrix: let's say matrix.dat and I want to extract the diagonal, subdiagonal and upper diagonal from it, to create a new tridiagonal matrix M. I know that with numpy you can get the diagonal, but is there any way to extract the…
Jack MR
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Passing multiple arguments in form of Dataframe and Arrays to fsolve in Python
I am trying to convert a matlab code into Python and need a help with fsolve function.
The Matlab function is of form
{[beta0,val,exitflag] = fsolve(@(beta) solve_obj(beta,y,x,z,z1), tb);}
where, y,x,z and z1 are given arguments and function need to…
chaoticjoker
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0
votes
1 answer
Why does some garbage appears instead of array values?
I take equation from a user (ex: 1X1+2X2=24 )
whatever the number of variables , i am toking it to 1X1 ,2X2 by +, - or =
and then put them in array of char and each toking by x or X, and put it on another array ,but some garbage comes…
Ahmed Awaad
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vpasolve return an empty sym 0x1 variable, while system clearly does have a solution (Matlab)
When I run this code I get empty strings for when setting a range for vpasolve, when I do not set the range I only get one solution, even with random on.
The range is set so that it does include the one solution matlab gives me, x=2, y=0 and…
Bob van de Voort
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1 answer
Solving integral for x in MATLAB, where x is bound and part of the integrand
I am trying to solve an equation for x in Matlab, but keep getting the error:
Empty sym: 0-by-1
The equation has an integral, where x is the upper bound and also part of the integrand 1. The code I use is the following:
a = 0.2; b= 10; c = -10; d…
Mike Lang
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1 answer
nleqslv, R, nonlinear equation system
I have the following nonlinear equation system:
r1*r2*(0.25*0.6061-0.5)+r1+(0.25*r2) = 0.6061
r1*r2*(0.25*0.6429-0.5)+r1+(0.25*r2) = 0.6429
I need to find the r1 and r2. Their solution should be equal to:
r1 = 0.5754
r2 = 0.6201
which resulted…
Amir Aliakbari
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Error using linsolve: Matrix must be positive definite
I am trying to use compressed sensing for a 2D matrix. I am trying to run the following piece of code -
Nf=800;
N=401;
E=E(Nf,N); %matrix of signal(this only for sampling) real matrix E is 2D matrix with size of Nf and N
% compressive…
Neda
- 9
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0
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1 answer
Making Sympy's system of equations iterable
I am trying to figure out an efficient way for solving systems of equations in Sympy "automatically". Let me exemplify, this is a standard approach to formulating the code
n = 3
y = sp.symbols('y1:{}'.format(n +…
Layman Tucker
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