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Alex Sha

94 total contributions since 2019

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I have two equations that are difficult to solve, so I am using fsolve to get the sol. But while running the program I encountered the error .Please help me or tell other way to solve these equations.
there are two solutions: 1: F1: 0.458069398988435 f1: -1.13829069933547 2: F1: 0.280093672719386 f1: 0.0244403974479464

ongeveer 3 uur ago | 0

Why I cannot get a solution for this system?
A set of approximate solutions： lfd: 0.273760301072663 r1d: 0.0994325019367128 l1d: 0.236671205261253 l1q: 0.077183609924249...

1 dag ago | 0

i have system of 15 equations and 15 unknown when i use (vpasolve) after 45 minit i have solutions with Warning: Solutions might be lost. [solvelib:​:allvalues​_warning]
Hi, it is easy to get the results below: y1: 4.99999995833333E-5 y2: 0.000199999986666668 y3: 0.0199999966666674 y4: 0.99999...

1 dag ago | 0

vpasolve: numeric instability when solving a system of three quadratic equations
The unique stable results are: u: 0.241646208739371 v: -1.29626943837113 w: 2.05462322963176

1 dag ago | 0

Fitting Data to a Non-Linear Curve
If don't care the function type, the follow is one: y = p1*(p2^x)*(x+p3)^p4; Root of Mean Square Error (RMSE): 0.0032240913289...

2 dagen ago | 0

Curve Fit data using FIT
the fit function "myEqn='(-a/(1+exp(c*((x-b)/h).^2)-1))+d'" is not correct, refer to: the function should be: myEqn='(-a/(1+e...

7 dagen ago | 0

Problem with fsolve: system of 6 nonlinear equations and more
a stable results: thot_membrane 470.276797155953 tcold_membrane 470.271756744994 thot_out -727.941719280904 thot_coolingplat...

9 dagen ago | 0

Trying to solve a system of equations with 14 equations and 14 unknowns
One result I got: a: 9.16543127083558 d: -3.41610736637613 v: 0.0215111341146459 re: -56206.8082673153 f: -0.00113861533204...

10 dagen ago | 0

Solution to 8 non-linear equations.
for the case: a1= 4.8994; a2=5.143; a3= 4.09248; a4= 6.264; a5= 3.7584; a6= 2.81184; a7= 5.568; a8=4.176; g1=0.00001; ...

12 dagen ago | 0

Solving the root of 5 equations with 5 unknowns.
Hi， Kaleb Crook， refer to the below results: x1: 0.0481826850207524 x2: 0.0410231263942099 x3: 0.0404768236956547 x4: 0.0777...

12 dagen ago | 0

find a function that approximates a given set of data imposing conditions

16 dagen ago | 0

Can I use patternsearch to solve a system of non-smooth equations?
Ho, provide your 42 equations in details, so others may try to solve

22 dagen ago | 0

How to curve fit following summation equation in MATLAB with given experimental data.
Hi， Yadav, I actually use a software package other than Matlab, named 1stOpt, it is much easy for using without guessing initial...

27 dagen ago | 1

How to curve fit following summation equation in MATLAB with given experimental data.
d(K/ (1+exp(c-b*t)))/dt=k*exp(c-b*t)*b/sqr(1+exp(c-b*t)),so your fitting function become: is the above correct? if yes, you m...

28 dagen ago | 0

| accepted

How to curve fit following summation equation in MATLAB with given experimental data.
Hi, Yadav, in your function "a*d/dt(k/1+exp(c-b*t))", what is "d/dt"? does "k/1" equal to "k"? Please describe clearly.

29 dagen ago | 1

Least square curve fit
The function of lsqcurvefit use local optimization algorithm, so it is too weak on fault tolerance, try to use global optimizati...

ongeveer een maand ago | 0

lsqcurvefit for global fitting gives bad parameters
Hi, I have just try to solve this complex fitting problem by using another math package, the result is as following, seems to be...

ongeveer een maand ago | 0

How to fit a quadratic equation to the experimental data by manipulating quadratic coefficients?
If you don't care the type of fitting function, try the following one: y = p1+p2*x+p3*x^3+p4/x+p5/x^2 Sum of Squared Residual:...

ongeveer een maand ago | 0

Exponential fit by customised equation
Hi, Sushreesmita Mishra, the problem you met is normal. When chose build-in function for data fitting, since "build-in", so Matl...

ongeveer een maand ago | 0

| accepted

Problem by star values lsqcurvefit
Hi, Zuyu An, what's your exact data? xdata = [0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 0.06 0.065 0.07 0....

ongeveer 2 maanden ago | 0

lsqcurvefit fitting not good
whether fminsearch or lsqcurvefit in Matlab use local optimization algorithms, it is why the initial start values are so importa...

ongeveer 2 maanden ago | 0

Fitting Monod Equation with ODE45 to data using lsqcurvefit function
Hi, Vinoj Liyanaarachchi, the code have been provided above alreadly, but note, that code is not for Matlab, but for another pac...

ongeveer 2 maanden ago | 0

Fitting Monod Equation with ODE45 to data using lsqcurvefit function
The follow results obtained from 1stOpt may be used for comparison: Code: Variable t,x,s,p; ODEFunction x'=umax*s*x/(ks + s);...

ongeveer 2 maanden ago | 0

curve of best fit from a few points
The equation below is good enough: y = p1+p2/(p3-x)^2; Root of Mean Square Error (RMSE): 0.000924797017843405 Sum of Squared ...

ongeveer 2 maanden ago | 0

What function fits my data...?
The follow function is much simple, but more better: y = x/(p1+p2*x)+p3 Root of Mean Square Error (RMSE): 0.313525722040886 S...

ongeveer 2 maanden ago | 1

| accepted

Curve fitting by Genetic Algorithm
Rerfer the results below: Root of Mean Square Error (RMSE): 0.00353350868235726 Sum of Squared Residual: 0.00029965640659906 ...

ongeveer 2 maanden ago | 1

Fsolve- equation solved, inaccuracy [possible
If want all are positive, refer the results follow: x1: 0.0990335590812945 x2: 1.27592369827812E-11 x3: 650.000000000022 x4:...

ongeveer 2 maanden ago | 0

fitting scatter data into multiple cosine functions
So, an gao, what is the result you want? Unless you add range constraint for all parameters (except w), because there are trigon...

ongeveer 2 maanden ago | 0