Reading matrix from file

The preview function shows data from the first worksheet by default. The first eight variables in the file contain numerical data. Configure the values in the opts object to import 10 rows for the first five variables from the worksheet named ''.

Preview the data from a spreadsheet file and import numerical data, as a matrix, from a specified sheet and range. Do I need to return an array with the m and n dimensions of the matrix or can I access the variables that I created in main and change their value within the external function? I prefer if someone would explain the second I don't actually know how to use pointers and stuff.

Sorry for my English, I'm not a native speaker, also thanks for your response. Even if you modify it, the caller won't see anything change.

This is basic knowledge that is covered in your C learning material. Most likely in the chapter dealing with pointers and the one dealing with function calls. Here's the catch. I tested your code and it works nicely. The problem is, what you want to achieve is only possible by using dynamic memory allocation. Take a look at the malloc and free functions. In C language you are responsible for allocation a space in memory for variable length data structures.

Pointers just store an address to a specific memory space allocated to the desired data type. In this example, you are just giving p an address to the first integer from n integers you just allocated. Matrix Programs. Explore more matrix programs. How are we doing? Please help us improve Stack Overflow.

Take our short survey. The primary benefit of this function is that named rows and columns can be used as opposed to integer indexes, as compared to the slam package. The other main motivation is that if the memory is available, dense matrix calculations can be faster than their sparse counterparts, not to mention having a wider range of operators available.

The names are expected to be comma separated in a single line. Various methods can be used to construct a sparse matrix representation that is used as the basis for constructing the dense matrix. Usage read. This is my function to read a matrix from a file. In the text file I have on the first line 2 is n and 3 is m and on the next two lines is the matrix.

I don't have erros, but my program "stop working" and I don't know why. Thank you! In main I have: readmatrix n,m,a, "text. Note that this is a basic example, you should always check the return value of fscanf.

If file. Also there are not numbers in the file, you would get also undefined values in the matrix. I'd advice to read the whole line with fgets and then parse the line using sscanf or some other function like strtok , then it would be easier to react to errors in the input file. In this example I calculate the number of columns only for the first column and use that number for all other columns.

If the input file has rows with less columns that the first row, then the missing values are stored with 0. If it has rows with more columns than the row will be trimmed. First I declare a pointer scan to point to line , so that I can modify the pointer without losing the original line. I used that to loop the sscanf.