Thread Subject:

Data Importing and Loop problem in Matlab

I am new learner of Mat lab. I want to transfer a big following data from excel into Mat Lab. In Mat lab, I am interested to find polynomial of X (constant) with different values of Y to get polynomial of each. Then I want to double differentiate each polynomial with respect to X and put equal to zero. Then I want to solve this equation to get value of X.
X: 1 2 3 4 5 6 7 8
Y: 9 8 7 6 5 4 3 2
Y: 7 6 5 4 3 2 1 0.5
Y: 9 7 6 5 4 3 2 1
---------------
--------------

In this procedure I am facing following problems.
1- What should be format of file in importing data into Matlab
2- I will use coef = Polyfit(x,y,n) to get coefficient of equation. But, in Mat lab, I cannot find differentiation by using coefficient of an equation.
3- How will I write the loop of program because there are lot of values

"Nadeem " <nadeemandmaaz@gmail.com> wrote in message <i6qjla$4eb$1@fred.mathworks.com>...
> I am new learner of Mat lab. I want to transfer a big following data from excel into Mat Lab. In Mat lab, I am interested to find polynomial of X (constant) with different values of Y to get polynomial of each. Then I want to double differentiate each polynomial with respect to X and put equal to zero. Then I want to solve this equation to get value of X.
> X: 1 2 3 4 5 6 7 8
> Y: 9 8 7 6 5 4 3 2
> Y: 7 6 5 4 3 2 1 0.5
> Y: 9 7 6 5 4 3 2 1
> ---------------
> --------------
>
> In this procedure I am facing following problems.

> 1- What should be format of file in importing data into Matlab
excel is fine:
help xlsread

> 2- I will use coef = Polyfit(x,y,n) to get coefficient of equation. But, in Mat lab, I cannot find differentiation by using coefficient of an equation.

If you have the symbolic toolbox then you can using diff(), solve(). If not, then you'll need to proceed numerically.

> 3- How will I write the loop of program because there are lot of values