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**Content Feed**

Question

Minimize variable by changing 3 coefficients

I have a complicated code with several functions. But ultimately, I want to change 3 variables in one function to minimize a dif...

2 years ago | 0 answers | 0

### 0

answersQuestion

sfit decimals output only 4 sig figs

I have a code that fits coefficients of a polynomial to data. I can access these polynomial coefifcients that are fit through a ...

3 years ago | 1 answer | 0

### 1

answerQuestion

create array of arrays from a single array

I have an array that looks like this: 0.000100000000000000 85 0.710500000000000 -0.118400000000000 0.00136500000000000 1.4070...

3 years ago | 1 answer | 0

### 1

answerQuestion

Reading a text file and creating arrays

I have a large text file that basically has this format: # index 13 # P = 0.0005 GPa 85 0.7100 -118.2e-3 1.364e-3 1.408 ...

3 years ago | 1 answer | 0

### 1

answerQuestion

find first time where data crosses 1

I have data stored in variables r and f. At some point the variable f goes above 1. How can I return the value of r the FIRST ti...

3 years ago | 2 answers | 0

### 2

answersQuestion

solving a very complicated equation implicitly

Hello, I have a very complicated equation that needs to be integrated and solved implicitly. I am not sure if MATLAB can handle ...

3 years ago | 2 answers | 1

### 2

answersQuestion

Solving for coefficients in polynomial

I have the following equation in MATLAB which solves for my coefficients: A45 = [(eta./eta_c).^(4:7).*(4:7)]\(Z_MD - Zfixed);...

3 years ago | 2 answers | 0

### 2

answersQuestion

fitting a funciton with minimax error

I am trying to solve a constraint problem regarding minimax error. Basically, I want to fit data to a specific type of function ...

3 years ago | 2 answers | 0

### 2

answersQuestion

fitting 2 variable function to (x-1) form

I have this fit currently which works great: fitobject = fit([r,eta/eta_c],H,ft,'problem',knownVals) However, because of the n...

3 years ago | 1 answer | 0

### 1

answerQuestion

variable needs to be array but only returning 1 value

I have a code that I am trying to vectorize but I must be missing something: This code below is part of a bigger loop, but I ...

3 years ago | 1 answer | 0

### 1

answerQuestion

plotting separate parts of a column on different figures

I have a large matrix. In the 3rd column, I have my "eta" values. In my 4th column, I have "r" values. In my 8th column, I have ...

3 years ago | 1 answer | 0

### 1

answerQuestion

plotting surface as function of two variables

I have a code that is a function of two variables below: How can I loop through the values of rpf and x and plot the function rd...

3 years ago | 0 answers | 0

### 0

answersQuestion

Constraining fit to two-variable function

Hello, I have the following code, which produces a surface of my data. (Example xlsx file attached). Certain coeffs are alrea...

3 years ago | 1 answer | 0

### 1

answerQuestion

Adding constraints to lsq fitting

I have a code that is of a function g(X,Y). The below code fits my data very well. However, I want to add some constraints at th...

3 years ago | 3 answers | 0

### 3

answersQuestion

initlalize several variables at once

I currently have a code where I am initializing many parameters, that will be solved for later. I do this by: C1=params(1)...

3 years ago | 4 answers | 0

### 4

answersQuestion

taking jacobion of function

I am using the lsqcurvefit function to fit a function that is dependent on two variables. Let's call these two variables, X, and...

3 years ago | 1 answer | 0

### 1

answerQuestion

General Approach to Fitting dozens of curves using the same coefficients

I have 30 data sets. Each data set corresponds to a different value of eta. So data set 1, consisting of x values and y values, ...

3 years ago | 2 answers | 0

### 2

answersQuestion

plotting on curve given only x value in a loop

I have the following code: for i=1:1:10 plot(data{1, i}(:,2),data{1, i}(:,4)); C = data{1, i}(:,4)./data{1, i}(:,2)...

3 years ago | 1 answer | 0

### 1

answerQuestion

numerical integration and solving for limit

I have the following equation: g(x) I have as a matrix in an array. It has an x and y column. So I want to take g(x) at a g...

3 years ago | 1 answer | 0

### 1

answerQuestion

Reading in a text file and creating multiple arrays

I have a large text file. The first two lines appear as follows: // cor=0.2 n=4000 N=10000 // r u_effe averg Below that ...

3 years ago | 1 answer | 0

### 1

answerQuestion

adding legend that is comes from a variable

I have a variable that looks like this: eta = [0.4843 0.3927]; Note that I access both of these later in a loop. How c...

3 years ago | 1 answer | 0

### 1

answerQuestion

Adding an outer for loop for a plot

I have the following code: eta = 0.4; eta_c = 0.6; rpf = eta/eta_c; count = 0; for x = 1:0.01:1.5 count = count + 1; ...

3 years ago | 2 answers | 0

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answersQuestion

plotting in a loop with a function

I have the following code: for x = 1:0.01:1.5 z = g(x,rpf); end but when I run this (assume my function is correct), I o...

3 years ago | 1 answer | 0

### 1

answerQuestion

gradient of a gradient giving drastically different answer than the del2 operator

I took a derivative of a derivative using the gradient method. I then applied the del2 operator to take the second derivative di...

3 years ago | 1 answer | 0

### 1

answerQuestion

Is there a way to directly take the second derivative of data?

In MATLAB, can I take the second derivative of data directly? Or do I need to take the derivative first using gradient, and then...

3 years ago | 2 answers | 0

### 2

answersQuestion

How to plot lines instead of symbols in loop

In the code below, it works fine. When I change '-o' to '-' , it does not plot anything, I am guessing the data gets dele...

3 years ago | 2 answers | 0

### 2

answersQuestion

Length of elements in array that are not NaN

I am trying to get the length of an array, and exclude NaN values. At the end of the column there are some NaNs. How can I ignor...

3 years ago | 1 answer | 0

### 1

answerQuestion

Loading in excel data with loop and plotting

I took 2 pieces of code and tried to put them together, but it did not work. When I load in data like this: S=struct; ...

3 years ago | 0 answers | 0

### 0

answersQuestion

plotting a struct in a loop

I have this code: semilogy(S.A600(:,1),S.A600(:,2)); I also want to plot S.A601 up to S.A620 This does not work...

3 years ago | 1 answer | 0

### 1

answerQuestion

Using xlsread in a for loop

I have this code: filename = 'C:\PATH\variable_analysis.xlsx'; A= xlsread(filename,'0.600'); But I want to read i...

3 years ago | 1 answer | 0