# raha ahmadi

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**Content Feed**

Question

In spite of being real, I get the error: Warning: Imaginary parts of complex X and/or Y arguments ignored.

Hi every one. I have a system of ODE. My solution is real (isreal (A_ODE)=1), but I get this error: Warning: Imaginary parts of ...

5 months ago | 1 answer | 0

### 1

answerQuestion

Difference between bode and my calculation of amplitude of the frequency response

Hi every one, I want to calculate the frequency response of a system, for example : I dont know why my answer is different fr...

7 months ago | 1 answer | 0

### 1

answerQuestion

How to find the roots of a trigonometric equation?

Hi, I want to determine the roots of a trigonometric equation : , e and \theta_c are constant. I try with 3 methods: Metho...

9 months ago | 2 answers | 0

### 2

answersQuestion

Plotting 4D function

Hi, I exported temperature vs cordinates(x,y,z) from COMSOL. I dont want to use LiveLink. I was wondering is there any method to...

1 year ago | 1 answer | 0

### 1

answerQuestion

Finding the intersection points between two curves

I need to find the intersection points of this equation: this is my code. I dont know what is the best way . Also when I plo...

1 year ago | 2 answers | 0

### 2

answersQuestion

Calculation the integral of the exponential of a matrix

I want to integrate of an exponential of a matrix ( E= exp (Mmat.*(t0-t))). First of all ‘expm’ built-in function in MATLAB ...

1 year ago | 1 answer | 0

### 1

answerQuestion

integral of a matrix

I want to take the integral of an exponetial of a matrix but I got this error and dont know how fix it: 'Unable to perform assi...

1 year ago | 2 answers | 0

### 2

answersQuestion

Getting Nan after using expm

Hi H dont know why I get Nan in situatin A but not in B. Thanks in advance % situation A r=[1e5,0,0; 0,-2e5,0; 1,1,...

1 year ago | 1 answer | 0

### 1

answerQuestion

Taking a long time to run, what is the problem?

Hi , I really nead help with this code. I dont know what makes it so long. I want to solve a PDE by extending it based on orthog...

1 year ago | 0 answers | 0

### 0

answersQuestion

smoothing a curve efficiently

Hi , I need to make my curve smooth and I use all of the method simoltaneouly but my data need to be more smooth. how can I ...

1 year ago | 2 answers | 0

### 2

answersQuestion

calculation of inverse matrix

I need to calculate the inverse matrix of P2 but I dont know my matrix is sparse or not. also I knew that this problem was solv...

1 year ago | 0 answers | 0

### 0

answersQuestion

Reference to non-existent field although the field is determined

Hi, I m working on a POS algorithm for optimizing an elemet of a matrix which is produced of multiplication of almost 1000 matr...

1 year ago | 1 answer | 0

### 1

answerQuestion

Undefined function or variable for struct variable

I have defined 'createModel' function but when I call struct variables from command window , for example model.pmin(5) or un...

1 year ago | 0 answers | 0

### 0

answersQuestion

Problem with solving the inhomogeneous systems of ODE

Hi, I 'm trying to solve a system of ODE neumerically, in these equaions I have a funcion of time ,Pc, which was calculated sepe...

2 years ago | 0 answers | 0

### 0

answersQuestion

numerical solution of a system of ODE which is not in standard form

Hi I' m wondering can MATLAB solve a system of ODE of these forms numerically? H11*dydt+H12*dxdt=H13 H21*dydt+H22*dxdt=H23...

2 years ago | 2 answers | 0

### 2

answersode45 solver code for solving a system of three coupled equations does not work

Thank you so much for your great help with Best wishes

2 years ago | 0

Question

ode45 solver code for solving a system of three coupled equations does not work

Hi , I have a system of three ordinary equations and want to solve them numerically. I wrote them with two methods but they hav...

2 years ago | 2 answers | 0