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Alex Sha


Last seen: 1 jour ago
150 total contributions since 2019

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  • 12 Month Streak
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  • Knowledgeable Level 2
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Answered
Using vpasolve to iterate/solve for flowrate in a piping network
refer to the result below: f1: 0.013713131883721 v1: 1.36937309476078 re1: 409175.227518161

environ 2 mois ago | 0

Answered
Solving set of 5 non-linear simultaneous equations using fsolve
Hi, Anahita, if you don't want complex answers, then there are problems in your eauqtions, here taking second equation as an exa...

environ 2 mois ago | 1

| accepted

Answered
Deconvolution of Guassian curve
Hi, you may try 4 Gauss Function: The results will be: Root of Mean Square Error (RMSE): 451.21462729511 Sum of Squared Res...

2 mois ago | 2

Answered
curve fitting toolbox for y=y0.exp((x0/x)^v) where data is known, but y0,x0 and v are unknown constants
Hi, Em, if fit as the function: y=y0.exp((x0/x)^v), then the result will be about: Root of Mean Square Error (RMSE): 9.39279339...

2 mois ago | 1

Answered
Nonlinear regression with two variables
Hi, Dipon, post your y, T and pH data please, if possible.

2 mois ago | 0

Answered
How can I solve this system of equation
Hi, VinceUgo, the eqn8 and eqn9 can be combined into one equation, so your problem become a system equation solving with eight e...

3 mois ago | 0

Answered
Fitting data to an equation with complex part
lsqcurvefit is seneitive to initial start-values since it use local optimization algorithm, same as cftool, there is a GA toolbo...

3 mois ago | 0

| accepted

Answered
Failure in initial objective function evaluation. FSOLVE cannot continue
You have three equations with three unknown parametrs, but initial start-values, you provide two only (x0=[1 1];), is this your ...

3 mois ago | 1

Answered
i need to solve 7 nonlinear equations with 7 unknows
refer the results below: Constant G x2 x1 x4 x3 x5 x6 x7 600 301.524350251906 299.992603098721 301.890052790606 305.9220213239...

3 mois ago | 0

Answered
Problems fitting couple differential equations to experimental data
Hi, if possible, upload your data (t, P and M) please

3 mois ago | 0

Answered
How to improve accuracy in fsolve?
There are multi-solutions with high enough accurancy, even given the range limition in [0, pi/2]: 1: a1: 0.996298496311242 a2...

3 mois ago | 0

Answered
Create a model to solve an energy balance
Hi, I get two solutions: No. 1 2 tg -328.861557610457 -549.471818197512 tm 1.72830356360143 -541.712011528394 hrpg -0.007275...

3 mois ago | 0

Answered
Fitting a profile to a Guassian Model
Hi, would you please upload your data file (dependent: alpha, independent variables: Temperature T, Pressure P, mass flow rate m...

3 mois ago | 0

Answered
How to fit complicated function with 3 fitting parameters using Least square regression
Hi, you may try to use "lsqcurvefit" command or curve fitting tool box (cftool), it is also better if you post data as well as k...

3 mois ago | 0

| accepted

Answered
Why is this not working
There are another five more solutions: No. x1 x2 x3 x4 x5 x6 x7 x8 x9 1 300 200 200 0 0.0447213595499958 -0.0447213595499958 3...

4 mois ago | 0

Answered
Fsolve complex results make no sense
Hi, Frederic Kluser, with your second case of Eq(9), I get the results below, all seem to be prefect: p: 1.79143003389998 p1_h...

4 mois ago | 0

Answered
Optimization of 9 unknown with 9 nonlinear constraints by fmincom
one inequality constraint is: x(1)-x(2)+x(3)-x(4)+x(5)-x(6)+x(7)-x(8)+x(9)<=0 (1) while one of equality constraint is: J*(x...

4 mois ago | 1

Answered
How to guess initialization parameters for non-linear curve fitting with nlinfit?
Hi, Aindrila, guessing the initial start value is always a difficult task since the local optimization algorithms are adopted in...

4 mois ago | 0

| accepted

Answered
using least square fit to find the best fit parameters
Hi, Annie, upload your data file please, if possible.

4 mois ago | 0

Answered
How to solve 3 non-linear equations with 3 unknowns?
One of numerical solution looks like: x: 4.49127153145489E-101 y: 0.0437692354838294 z: 867273686630772

4 mois ago | 0

Answered
How can I fit this data?
Hi, toon, how about the model function below: z = (p1+p2*x+p3*x^2+p4*y+p5*y^2)/(1+p6*x+p7*x^2+p8*x^3+p9*y+p10*y^2); where x: s...

4 mois ago | 0

Answered
How do I find the coefficients of a function for a curve fit?
The below should be the best solution: Root of Mean Square Error (RMSE): 0.0255893453091926 Sum of Squared Residual: 0.0471466...

4 mois ago | 0

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...

4 mois 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...

4 mois 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...

4 mois 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...

4 mois 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 mois 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...

5 mois ago | 1

| accepted

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