I am trying Julia and have made some notes on equivalent syntax in Julia and Fortran.
Below the Julia syntax appears first and the Fortran syntax appears after “vs.”. Additions are welcomed.
x = 1.0 vs. x = 1.0d0 (Julia uses 64-bit floats)
x = zeros(5) # array of Float64 intialized to zero
vs.
real(kind=kind(1.0d0)), allocatable :: x(:)
allocate (x(5),source=0.0d0)
[] vs. () to index array elements
true and false vs. .true. and .false.
& vs .and.
| vs. .or.
! vs. .not.
^ vs. ** for exponentiation.
x = rand(n) puts n uniform random variates in x,
x = rand(n1,n2) fills a matrix with dimensions [n1,n2]
sum(x) like Fortran
sum(x,dims=1) vs. sum(x,dim=1)
sum(x,dims=[1,2]) = sum(x) for 2-D array
In general, Julia has a dims optional argument for array functions vs. dim in Fortran,
minimum() and maximum() vs. minval() and maxval()
size(x) returns tuple, size(x,dim) returns scalar. Fortran size(x) returns a scalar.
size(x) vs. shape(x)
length(x) vs. size(x)
x = [2,3] creates a 1-D array of integers
x = [2,3.1] creates a 1-D array of Float64, [2.0,3.1]. The integer value is coerced to Float64.
vec(x) converts x to 1-D array, vs. [x]
x .> 0 vs. merge(1,0,x>0) Note the . before >.
x[x .> 0] vs. pack(x,x>0)
* vs. // to concatenate strings
rstrip("foo ") vs. trim("foo ")
println(2," ",5) vs. print*,2,5 – Julia does not insert spaces between printed items by default.
print(2) vs. write(*,"(i0)",advance=“no”) 2 – Julia print does not append newline, unlike println
# vs. ! for comments
dog and Dog are distinct variables, unlike Fortran
loops:
for i in 1:3
println(i," ",i^2)
end
vs.
do i=1,3
print*,i,i**2
end do
if blocks:
if someVar > 10
println("someVar is totally bigger than 10.")
elseif someVar < 10 # This elseif clause is optional.
println("someVar is smaller than 10.")
else # The else clause is optional too.
println("someVar is indeed 10.")
end
vs.
if (someVar > 10) then
print*,"someVar is totally bigger than 10."
else if (someVar < 10) then ! This elseif clause is optional.
print*,"someVar is smaller than 10."
else ! The else clause is optional too.
print*,"someVar is indeed 10."
end if
function definition:
function power(i,a)
return i^a
end
vs.
integer function power(i,a)
power = i**a
end
