Fortran Help with declaring arrays in Fortran 90/95

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To calculate the least squares fit line for a user-defined number of points in Fortran, it's essential to use allocatable arrays instead of fixed-size arrays. The initial approach of declaring a fixed-size array based on user input leads to errors, as Fortran requires variable declarations before any read/write operations. By utilizing allocatable arrays, you can dynamically allocate the necessary memory after determining the number of points the user wishes to input. This method resolves the issue of needing to know the size of the arrays beforehand and adheres to Fortran's requirements for variable declarations.
warfreak131
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I have an assignment to calculate the least squares fit line to a set of points, and I have to read in an arbitrary number of points from the user

So my plan was to have the user enter how many elements they have, and then create an array with that many elements. So let's say I read the value N from the user, and then create an array like:

Code: 
real, dimension(N) :: xvals, yvals

But that's a no-no according to fortran. If any read/write statement goes before declaring the variables, I get a whole host of errors. However, if I remove those read/write statements and create a set number of array elements like:

Code: 
real, dimension(10) :: xvals, yvals

then all the error go away. Unfortunately, I have to find out how many variables the user wants before creating the array.
 
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You need to learn how to use allocatable arrays. Googe it and learn the syntax. It is pretty easy.
 
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