Risposto
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...

oltre 4 anni fa | 0

Risposto
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...

oltre 4 anni fa | 0

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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 ...

oltre 4 anni fa | 1

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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...

oltre 4 anni fa | 0

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

oltre 4 anni fa | 0

Risposto
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...

oltre 4 anni fa | 0

Risposto
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...

oltre 4 anni fa | 0

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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...

oltre 4 anni fa | 0

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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...

oltre 4 anni fa | 0

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Risposto
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...

oltre 4 anni fa | 0

Risposto
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...

oltre 4 anni fa | 0

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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...

oltre 4 anni fa | 1

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I am solving 20 nonlinear equation using fsolve to find 20 variables' value. But i previously know one of variable's value. That variable is x(17) in eqn F(17). x(17)=1200. Based on this fixed variable i want to find remaining variables' value.
The equation F(17) seems to be meanless: F(17)= (100e6*((0.5*(x(5)*x(6)+x(7)*x(8)))+(0.5*(x(11)*x(15)+x(12)*x(16))))/(-C*x(17))...

oltre 4 anni fa | 0

Risposto
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...

oltre 4 anni fa | 0

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

oltre 4 anni fa | 0

Risposto
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

oltre 4 anni fa | 0

Risposto
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...

quasi 5 anni fa | 0

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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...

quasi 5 anni fa | 0

Risposto
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...

quasi 5 anni fa | 0

Risposto
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...

quasi 5 anni fa | 0

Risposto
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...

quasi 5 anni fa | 0

Risposto
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...

quasi 5 anni fa | 1

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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...

quasi 5 anni fa | 0

Risposto
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...

quasi 5 anni fa | 1

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Risposto
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.

quasi 5 anni fa | 0

Risposto
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

quasi 5 anni fa | 1

Risposto
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...

quasi 5 anni fa | 0

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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.

quasi 5 anni fa | 0

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

quasi 5 anni fa | 0

Risposto
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...

quasi 5 anni fa | 0

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