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

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

1 year 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...

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...

1 year 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...

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...

1 year 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...

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...

1 year 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...

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...

1 year 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...

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 year 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...

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 year 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...

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...

1 year 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...

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...

1 year 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.

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.

1 year 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

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

1 year 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...

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...

1 year 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.

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.

1 year 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....

fsolve & linsqnonlin cant solve my equations

The unique stable results: x1: 0.231780000872077 x2: 0.040000000119062 x3: 0.508699999227432 x4: 0.00060000005989538 x5: 4....

1 year 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...

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...

1 year 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:...

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:...

1 year 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...

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...

1 year 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 ...

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 ...

1 year 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...

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...

1 year ago | 0

Answered

Multiple equations solving in MATLAB

Hi, Golam, post out your problem, we may try.

Multiple equations solving in MATLAB

Hi, Golam, post out your problem, we may try.

1 year 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....

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....

1 year 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...

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...

1 year 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...

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...

1 year 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...

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...

1 year 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, ...

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, ...

1 year 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...

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...

1 year 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...

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...

1 year 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...

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...

1 year 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...

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...

1 year 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 ...

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 ...

1 year ago | 0