Today, I found this amazing site for Fortran tutorials - https://masuday.github.io/fortran_tutorial/index.html

I went through the tutorials which was organized in a very neat way. Then I proceeded to implement the following simple code.

Make a tridiagonal matrix with 1 on diagonal and 0 or on off-diagonal with an arbitrary $n$. See the following example for $n=5$. $$ \displaystyle{\begin{bmatrix} 1 & 0 & 0 & 0 & 0 \ 0 & 1 & 0 & 0 & 0 \ 0 & 0 & 1 & 0 & 0 \ 0 & 0 & 0 & 1 & 0 \ 0 & 0 & 0 & 0 & 1 \end{bmatrix} } $$ The following is my implementation.

Today had been two part work. Initially, I did some Data Structures lessons from Udacity course. Then, at night, I tried to implement the Single objective optimisation method called fibonacci method using Fortran. There is some mistake that I need to correct. I will share the updated code tmw. Here’s the faulty one!

Today I was able to cover a lot of stuff - mainly the exercises and some Gnuplot basics.

I’ve already made a blog post on the first exercise I worked on - Generate Logistic Map in Fortran. It was fun. Also, later I took a look at the solution available at the mooc’s repository. I was really impressed by how the code is organized. Everything looked neat and debuggable. Inspiring code, one could say! Here’s the link to the Julia set code in MOOC Github repository. This is where I came to know that functions in fortran can act upon an array without being specially defined for arrays.

I had been following the MOOC “Scientific Computing with Fortran” for a week and currently doing the exercises. This is one of the assignments which has piqued my interests - Logistic map. Here’s a neat animation from Wikimedia for the same.

Today, I was introduced to I/O in Fortran. Its a little complex for seemingly simple task. But, its good to have all the bells and whistles known upfront. Here is a sample program on input output.

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program inputoutput
    use, intrinsic :: iso_fortran_env, only : sp=>real32, dp=>real64, error_unit, input_unit
    implicit none
    integer :: unit_nr, istat
    integer :: a, b
    character(len=1024) :: msg
    ! IO Opening a file
    open(newunit=unit_nr, file='text.txt', access='sequential', action='write', &
    status='new', form='formatted', iostat=istat, iomsg=msg)
    if (istat /= 0 ) then ! Handling Error
        write (unit=error_unit, fmt='(3A)') 'error: ', trim(msg), istat
        stop 1
    end if
    ! Writing to a file
    write (unit=unit_nr, fmt='(A)') 'hello world'
    write (unit=unit_nr, fmt='(F4.2)') x
    close(unit=unit_nr)
    
    print *, "Enter the number"
    ! Reading input from user
    read(unit=input_unit, fmt='(I2)', iostat=istat, iomsg=msg) a
    print *, a+5

end program inputoutput

In Fortran IO, there are few points to note.

Today I had learnt about the procedures and intrinsic procedures in Fortran. Basically, a procedure can be of two types

• function
• subroutine

Functions

The functions are procedures which return a value which can either be

1. Given the same name as function name in which case the syntax will be.

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integer function function_name(inputname)
	implicit none
	integer, intent(in) :: inputname
	.
	.
	function_name = 1234..
end function function_name

In this case, the return type is given before function keyword. Also, note that in fortran, values are passed by reference by default. Hence, if the input is only an input, intent(in) needs to be mentioned. Other intents are out, inout.

Today I had continued with Fortran for Scientific Computing and learned about

• Character datatype
• Logical datatype and operators
• Conditional Statements

Character Datatypes

The character dataypes are declared as either a single character or as an array of particular length.

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character :: c
character(len=5) :: str

Two main points about strings are that,

This is my first day in the 100 Days of Code challenge. Today, I had started with the “Fortran for Scientific Computing” course in Future Learn. It had been a great start.

I had learnt about the precision available in fortran for various number data types. For example, the follow program deals with the single and double precision for real numbers.

In this post, we will look at a way of approximating deflection function of beams using Rayleigh Ritz method. I had been recently watching this (click here for youtube link) lecture series by Clayton Pettit which had been a very useful introduction to finite element methods. This is one of the assignment problems provided in that series.

I use the dark mode plugin for firefox so that there’s less eye strain at night times. But, since the new UI change of firefox, there’s flash of white light before the dark mode kicks in, even when the firefox theme is set to dark. I was looking for a solution and found the following in reddit.