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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...

4년 초과 전 | 0

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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...

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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 ...

4년 초과 전 | 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...

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

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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...

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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...

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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...

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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...

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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...

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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...

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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...

4년 초과 전 | 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))...

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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...

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

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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

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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...

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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...

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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...

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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...

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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...

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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...

4년 초과 전 | 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...

거의 5년 전 | 0

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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...

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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.

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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

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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...

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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.

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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....

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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...

거의 5년 전 | 0

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