010. Fortran arrays can have any lower bound (the default is 1)

topic: Arrays

Fortran arrays can have any lower bound. The default is 1. Array functions have optional mask arguments to determine the elements used.

array-lbound.f90 | | |

integer :: v(-1:1) = [1, -2, 3]

print *, lbound(v), ubound(v), size(v)  ! -1 1 3
print *, sum(v)  ! 2
print *, sum(v,mask=v>0)  ! 4 -- sum excludes -2

end

Output1

          -1           1           3
           2
           4

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Fortran arrays can have any lower bound.
The default is 1. Array functions have optional mask arguments to determine the elements used.

integer :: v(-1:1) = [1,-2,3]
print*,lbound(v),ubound(v),size(v) ! -1 1 3
print*,sum(v) ! 2
print*,sum(v,mask=v>0) ! 4 -- sum excludes -2
end

— FortranTip (@fortrantip) December 18, 2021

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Compiled using GNU Fortran (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0 with no flags