Alex Sha
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Contribute at least one answer each month for 12 consecutive months
Awarded to Alex Sha on 03 Apr 2020
Answer 10 questions that were unanswered for more than 30 days
Awarded to Alex Sha on 09 Jan 2020
3 of your answers have been accepted
Awarded to Alex Sha on 18 Sep 2019
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Awarded to Alex Sha on 22 Apr 2019
Content Feed
curve fitting a custom equation
Hi, all, as mentioned by Walter Roberson, the resule I provided above is obtained by using 1stOpt, the biggest advantage, for 1s...
13 days ago | 0
| accepted
I want to solve 2 equations with 2 variables but it cant be solved and the command window shows fsolve stopped because the last step was ineffective
Hi, the result below should be one solution x1: -52.5485799573576 x2: 12.1032014174617
27 days ago | 0
How to solve a system of second order nonlinear differential equations with boundary conditions
Hi, the chart will be given automatically in 1stOpt UI, also you can make chart yourself by using the result data given above. 1...
1 month ago | 0
I need to fits the attached data as in image
Hi, the fitting function "y = p1/(1+Exp(p2+p3*x)+p4*x)^p5" is pretty good for all data set, where y=L, x=T 1: T1-L1: Root of ...
2 months ago | 1
| accepted
Objective function is returning undefined values at initial point. lsqcurvefit cannot continue.
The best results are as below, hard to be obtained since the initial-start values are impossible to be guessed reasonally. Root...
2 months ago | 0
| accepted
Kinetic parameter estimation and initial time setting
Hi, see the results below: Root of Mean Square Error (RMSE): 4.00513564326846 Sum of Squared Residual: 320.822230419589 Corre...
3 months ago | 0
How to include contratins on 1 variables for this nonlinear system of equations?
Hi, refer to the solutions below: 1: x1: 0.415757622422666 x2: 0.321911265108838 x3: 0.0970690621849188 2: x1: 12.98212823...
4 months ago | 0
Fit points and specify the slope at one of the points
Hi, try the function below: y = p1+p2*x^2-p3*exp(p4*x); to ensure the slope being 0 in point of "x=0.985035", should add a con...
6 months ago | 0
solving set of non linear equation
Hi, refer to the results below: phi1: 0.00687835881390378 phi2: 3.07608732711163
6 months ago | 0
Trouble finding solution of unknown variable in difficult integration problem
Hi, there are two solutions as below: 1: h=0.073660616949704 2: h=0.165217787421255
6 months ago | 0
fsolve is not returning the right solutions
Hi, if you think the solutions should be (1,0,1) or (-1,0,1) , then one equation: F(3) = 1 + 2*x2.^2 + x3.^2; should be: F(3)...
7 months ago | 0
Solving lengthy nonlinear complex equations in complex variables
Try to find numerical solutions as below; y1s.realpart: 11.0169967890388 y1s.imagpart: -125.141575853451 y3s.realpart: 7.8197...
9 months ago | 0
Lsqnonlin_Fitting Data
Hi, if possible, please post out your data of each curve, as well as the fitting equation.
10 months ago | 0
How to Fit a line to scatter data on scatter plot?
Hi, Chetan, if you don't mind the length of the fitting equation, refer to follow: x1=Speed, x2=Dp, y=Eff y = b0+b1*x1+b2*x1^2...
11 months ago | 0
Fitting a Custom Sigmoid
Hi，if the fitting function is： 1：y=a1*exp(-a2*exp(x)) Root of Mean Square Error (RMSE): 0.291990919479646 Sum of Squared Resi...
11 months ago | 0
| accepted
Options when drawing using the Curve Fitting tool
Hi, post your data and function in txt format, if possible.
11 months ago | 0
| accepted
How could I do simutanoues parameter fitting for two series experimental data and multiple datasets?
Hi, post your data please, if possible
1 year ago | 0
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
1 year ago | 0
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...
1 year ago | 1
| accepted
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...
1 year ago | 3
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...
1 year ago | 1
Nonlinear regression with two variables
Hi, Dipon, post your y, T and pH data please, if possible.
1 year ago | 0
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...
1 year ago | 0
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...
1 year ago | 0
| accepted
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 ...
1 year ago | 1
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...
1 year ago | 0
Problems fitting couple differential equations to experimental data
Hi, if possible, upload your data (t, P and M) please
1 year ago | 0
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...
1 year ago | 0
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...
1 year ago | 0
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...
1 year ago | 0
