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Alex Sha


Last seen: Today
126 total contributions since 2019

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  • Revival Level 3
  • 6 Month Streak
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Answered
Matlab curve fitting two equations simultaneously with common arguments
Hi, Liu, your fitting functions are overdeterminted, there are multi-solutions: 1: Root of Mean Square Error (RMSE): 0.1634941...

16 minutes ago | 0

Answered
continuity of a fit function in different regions
Hi, the function below meets your requirements, with the derivative to be zero at x=1 y = p1+p2*(((x-p3)*(x+p4))^2)^p5; Root o...

environ une heure ago | 0

Answered
lsqcurvefit not adjusting some parameters as expected
The best solution seems to be: Root of Mean Square Error (RMSE): 8.58712889537096E-5 Sum of Squared Residual: 1.50943288116718...

1 jour ago | 0

Answered
Fit multiple data with one mathmatical model/function
Hello, AHMED, your fit function is overdeterminted which will lead to multi-solutions, the parameter of "a1" is redundant: C=a1...

1 jour ago | 1

Answered
How to fit a custom equation?
If don't care the type of fitting function, try the below function, much simple but with much better result: y = b1+b2*x^1.5+b3...

5 jours ago | 0

Answered
Fitting a sigmoid curve using curve fitting tool box
Hi, Hair, the quailty of your data seems to be bad for sigmoid type of function. If take the function like: y = y0+a/(1+exp(-(x...

6 jours ago | 1

| accepted

Answered
How can i solve the error "Reference to non-existent field 'xShape'. Error in finDiffEvalAndChkErr Error in finitedifferences'"
Hi, as my test, if c>0.367879, there is no solution for your equations.

10 jours ago | 0

Answered
Error fsolve undefined function or variable x.
taking initial start-values as: x0=[6 0.5 150]; will produce: x1: 5.96 x2: 7.50486851347978E-7 x3: 152.194203428967

14 jours ago | 1

Answered
Designing an iterative algorithm for a nonlinear system of equations
There are two set of solutions: 1 x1: 0.256953706774553 x2: -399.382730699003 x3: 0.0102597835062331 Fevl: 9.92301206481...

15 jours ago | 0

Answered
Solving a system of 5 dependent non-linear equations
My pleasure, it is actually very challenging problem, hard to be solved by common software or algorithms.

19 jours ago | 0

Answered
fsolve & linsqnonlin cant solve my equations
The unique stable results: x1: 0.231780000872077 x2: 0.040000000119062 x3: 0.508699999227432 x4: 0.00060000005989538 x5: 4....

20 jours ago | 0

Answered
Solving a system of 5 dependent non-linear equations
Hi, if vt = 0.0257, the solution should be: m: 512.891368076595 rsh: -1.08505661410065 rs: 3.40678689852078 io: 0.8568128664...

21 jours ago | 0

Answered
Solving a system of nonlinear equations with bounded variables
There are two solutions: 1: q_b: 0.305291000916417 q_v: 0.0179815487538954 q_lp: 0.237309452162523 y: 1.25168611470519 pr:...

21 jours ago | 0

Answered
Curve fitting with constraints
Hellow, Paul, if adding one more parameter in your fitting function, i.e. y = a*exp(b*x) + c*exp(d*x)+f Then: from y(0) = 0, w...

22 jours ago | 0

Answered
how to solve a system of non linear-equations
Hi, I get the solutions below: 1: r1: 0.0136978624480164 r2: -0.0529268624480211 c1: 23794.5028958407 c2: 1043438.64860562 ...

23 jours ago | 0

Answered
No solution found when solving 3 non linear equations
Hi, all, how about the solutions below, from the numerical perspective: 1: x1: -5.21219473201765E21 x2: -0.279500437676178 x...

26 jours ago | 0

Answered
Multiple equations solving in MATLAB
Hi, Golam, post out your problem, we may try.

26 jours ago | 1

Answered
8 nonlinear equations, 8 unknowns - little luck with fsolve/vpasolve
Hi, Alex Tekin, you may try some solvers or software package with the ability of global optimization, i.e. Baron, Lingo, 1stOpt....

26 jours ago | 1

| accepted

Answered
Non-linear Multivariate regression using genetic algorithm
The GA toolbox in Matlab is not an ideal tool for curve fitting with the goal of global optimizatiom result. Refer the result be...

26 jours ago | 0

Answered
fminsearch for fitting a function to experimental data
There seem to be two sets of solutions: 1: Root of Mean Square Error (RMSE): 2.45406561689894 Sum of Squared Residual: 78.291...

26 jours ago | 0

Answered
What is "Equation solved,fslove stalled'?
There are two solutions: 1: x1: -0.000499999999999997 x2: -2.28184863820141E-18 2: x1: -2.52247055758755E-18 x2: -0.000429...

environ 2 mois ago | 0

Answered
How can I find a correct value of the guess for my system of non linear equations ??
it is not easy to get correct initial start values, try to use global optimization algorithm instead of local ones like fsolve, ...

environ 2 mois ago | 0

Answered
Constrained Global Optimization Problem with MultiStart, GA and HybridFunction using Parallel Processing
the best results: Root of Mean Square Error (RMSE): 69.3464929074478 Sum of Squared Residual: 577072.329427525 Correlation Co...

environ 2 mois ago | 0

Answered
Failure in initial objective function evaluation. LSQCURVEFIT cannot continue.
Hi,Thaer Ismail, which is your exact fit function: "ydata=1-x1*exp(-(x2/xdata)^x3)" or "ydata=1-x1*exp((-x2/xdata)^x3)" ? if th...

environ 2 mois ago | 0

Answered
Least Square Curve Fitting, finding the initial start values in lsqcurvefit function in Matlab
if " the second and third number are 0.2 and 0.4.", then the result will be much better: Root of Mean Square Error (RMSE): 0.01...

environ 2 mois ago | 0

Answered
System of nonlinear equations
Hi,Mahboubeh, the results of your second case are much different with that of your first one, so in second case you use approxim...

2 mois ago | 0

Answered
How can i calculate five unknown parameters??
There are multi-solutions for Charalampos's problem: 1: iph: -12.4464463252524 io: -889977.402184639 n: -4891.45375599277 ...

2 mois ago | 0

Answered
I want to solve this equation. please help me
Here is the right solution, obtained from 1stOpt: a: -2.38880243947768E-9 b: 0.357245116257183 c: -32.3471147348507 d: -0.0...

2 mois ago | 1

Answered
Please help me to solve following equations using matlab
change the type of last three equations from (by removing denominator): 6.2975e-11 - (((x(6)^4)*(x(8)^8))/((x(4))*(x(5)^3)*(x(1...

2 mois ago | 0

Answered
Fslove don't find the right solution
I get the results: 1: q1: 31.25152 q2: -3.3648581278838E-15 q3: -37.1015437789933 2: q1: 31.2515200000001 q2: 1.378921962...

2 mois ago | 0

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