All Questions
25
questions
1
vote
1
answer
69
views
Find an instance satisfying equation
I have the following equation with two variables xi and nu.
...
- 496
1
vote
1
answer
86
views
Minimization of an implicitly specified function
exp - an experimental data, where expT - temperature, expChi - magnetic susceptibility
I ...
- 1,883
0
votes
0
answers
92
views
Why doesn't NMinimize work with NSolve?
Why does NMinimize throw the error and how to fix it?
...
- 1,883
0
votes
2
answers
109
views
Why can't NSolve find values that FindInstance can?
I am trying to solve for \[Epsilon], given three input paramters n, x and ...
- 496
0
votes
0
answers
54
views
Finding values of constants for which 1st and 2nd order derivatives of a function vanish
I'm trying to find critical values of some constants $v_c$ and $T_c$, for which holds the equality below:
$$\bigg(\frac{\partial P}{\partial v}\bigg)\biggr\rvert_{v=v_c,\; T=T_c}=0,\quad \bigg(\frac{\...
- 27
1
vote
1
answer
242
views
How to numerically solve an equation
I would like to solve for $r_2$ the following two (independent) equations:
$x_{Min}(a,b,c,r_1,F)=x_{Max}(a,b,c,r_2,F)$ (1)
and
$x_{Min}(a,b,c,r_2,F)=x_{Max}(a,b,c,r_1,F)$ (2)
where $a$, $b$, $c$, $r_1$...
- 77
0
votes
0
answers
36
views
Which result is more reliable in NMaximize in the given code? with `WorkingPrecision` or without it?
I have two functions $ f(x,y) $ and $ g(x,y) $ over the domains $ 1<x< 2$ and $0<y<\pi$. I use ContourPlot to ses those values of $(x,y)$ for which $g(...
- 749
0
votes
2
answers
216
views
How to calculate the maximum value of $x $ which satisfy the conditions $g(x,y)=0$ and $f(x,y)>1$?
I have two functions $ f(x,y) $ and $ g(x,y) $ over the domains $ 1<x< 2$ and $0<y<\pi$. I use ContourPlot to ses those values of $(x,y)$ for which $g(...
- 749
0
votes
1
answer
74
views
Formalization of one optimization problem or solution of inequalities - Part №2
Continuing the question: Formalization of one optimization problem or solution of inequalities
Let's consider a more complex problem. We have two polynomial:
$p_1=A_2t^2+A_1t+A_0$
$p_2=B_2t^2+B_1t+B_0$...
- 2,444
2
votes
1
answer
79
views
Formalization of one optimization problem or solution of inequalities
I have polynomial:
$p=A_2t^2+A_1t+A_0$
$A_0=(x^2-y^2)+xz$
$A_1=x^2+y^2+z^2+\sin(x)$
$A_2=x^4+y^3+z^2$
$x,y,z$ - parameters, moreover $z$ - the value of which varies in the range $[0,1]$.
Polynomial $p$...
- 2,444
1
vote
1
answer
139
views
FindRoot with a big range
I have a variable sig that is related to the variables (b,zQ,zh) given by torootsig, so I ...
- 715
1
vote
1
answer
99
views
Optimization of second order ODE with more than one parameter
I want to optimize a second order ODE with more than one variable:
...
- 91
0
votes
0
answers
128
views
FindMinimum Error - cvec: Constrained optimization is only supported with scalar valued variables
I want to solve a non-linear equation derived with a forward march finite difference technique (defined as "f" in the code). I am using FindMinimum, since I know an approximate initial value for each ...
- 1
5
votes
1
answer
505
views
Optimizing a parameter in an ODE
I've solved a system of two ODEs using NDSolve which look like this
$\qquad y''-ky'=c, \quad y(t=0)=y_0, \quad y'(t=0)=\sin(a)$
$\qquad x''-kx'=0, \quad x(t=0)=x_0, \quad x'(t=0)=\cos(a)$
Where $c,q,k,...
- 167
2
votes
1
answer
520
views
Find the minimum value of parameters that satisfy a set of conditions
I want to characterize the set of parameters that satisfy some conditions. One of the conditions is that the result of Solve/FindRoot is greater than zero.
Example:
...
- 393