Data update

Task/Display-a-linear-combination/Fortran/display-a-linear-combination.f

@@ -0,0 +1,94 @@
+! Display a linear combination
+! tested with Intel ifx (IFX) 2025.2.0 20250605             on Kubuntu 25.04
+!             GNU Fortran (Ubuntu 14.2.0-19ubuntu2) 14.2.0  on Kubuntu 25.04
+!             VSI Fortran x86-64 V8.6-001                   on OpenVMS x86_64 V9.2-3
+! Note that VMS requires switch $Fortran/ccdefault=LIST
+! otherwise 1st character of each output line is interpreted as
+! Carriage Control character.
+!
+! U.B., July 2025
+!
+program LinearCombinations
+
+implicit none
+
+! All test cases from Task Description
+!
+call showLinearCombinations ([1,  2,  3])
+call showLinearCombinations ([0,  1,  2,  3])
+call showLinearCombinations ([1,  0,  3,  4])
+call showLinearCombinations ([1,  2,  0])
+call showLinearCombinations ([0,  0,  0])
+call showLinearCombinations ([0])
+call showLinearCombinations ([1,  1,  1])
+call showLinearCombinations ([-1, -1, -1])
+call showLinearCombinations ([-1, -2,  0, -3])
+call showLinearCombinations ([-1])
+
+contains
+
+subroutine showLinearCombinations (v)
+
+  integer, intent(in) :: v(:)         ! Vector of coefficients
+  integer :: i                        ! Loop index
+  logical :: firstTerm                ! Indicates first non-zero term of each case
+
+  firstTerm = .true.
+
+  ! Now iterate through array of coefficients. Care for proper spacing.
+  ! Special cases:
+  !   coefficients 0: do nothing, just skip it.
+  !   coefficients 1 or -1: do not print 1 as factor for e(i)
+  !   all others:
+  !     first term:
+  !        if negative: print coefficient with minus sign
+  !        if positive: print  coeffivient without sign indicator.
+  !     all others; add/subtract  with spacing " + " resp. " - "
+
+  do i=1,size(v)
+    if (v(i) .eq. 0) then
+      ! zero coefficient: do nothing
+
+    else if (v(i) .eq. 1) then
+      ! coefficient is 1: dont print factor '1', just e(i)
+      if (.not.firstTerm) write (6,'(" + ")', advance='no')   ! first term is not added
+      write (6,'("e(", i0, ")")', advance='no')  i
+      firstTerm = .false.
+
+    else if (v(i) .eq. -1) then
+      ! coefficient is -1: dont print factor '-1', just "-e(i)" or "- e(i)"
+      if (firstTerm) then
+        write (6,'("-")', advance='no')         ! first term not subtracted, write -e(i)
+      else
+        write (6,'(" - ")', advance='no')       ! subtract with spacing "- e(i)"
+      endif
+      write (6,'("e(", i0, ")")', advance='no')  i
+      firstTerm = .false.
+
+    else if (v(i) .gt. 0) then
+      ! positive coefficient c: write "+ c*e(i)" except at start of line
+      if (.not.firstTerm) write (6,'(" + ")', advance='no')   ! no '+' at beginning of line
+      write (6,'(i0, "*e(", i0, ")")', advance='no') v(i),  i
+      firstTerm = .false.
+
+    else if (v(i) .lt. 0) then
+      ! Negative coefficient c: write "- c*e(i)" if not fist term, otherwise with sign '-'
+      if (.not.firstTerm) then
+        write (6,'(" - ")', advance='no')               ! minus with spacing
+        write (6,'(i0, "*e(", i0, ")")', advance='no') abs(v(i)),  i
+      else
+        write (6,'(i0, "*e(", i0, ")")', advance='no')  v(i),  i
+      end if
+      firstTerm = .false.
+    end if
+  end do
+
+  if (firstTerm)  then
+    write (6,'("0")')   ! no non-zero terms so far: print '0'
+  else
+    write (6,*)         ! printed some non-zero terms, terminate line.
+  end if
+
+end subroutine showLinearCombinations
+
+end program LinearCombinations

Task/Display-a-linear-combination/Pluto/display-a-linear-combination.pluto

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+local function linear_combo(c)
+    local sb = ""
+    local i = 0
+    for c as n do
+        if n != 0 then
+            local op = (n < 0 and sb == "") ? "-"   :
+                       (n < 0)              ? " - " :
+                       (n > 0 and sb == "") ? ""    : " + "
+            local av = math.abs(n)
+            local coeff = (av == 1) ? "" : $"{av}*"
+            sb ..= $"{op}{coeff}e({i + 1})"
+        end
+        ++i
+    end
+    return (sb == "") ? "0" : sb
+end
+
+local combos = {
+    {1, 2, 3},
+    {0, 1, 2, 3},
+    {1, 0, 3, 4},
+    {1, 2, 0},
+    {0, 0, 0},
+    {0},
+    {1, 1, 1},
+    {-1, -1, -1},
+    {-1, -2, 0, -3},
+    {-1}
+}
+for combos as c do
+    print(string.format("%-13s  ->  %s", c:concat(", "), linear_combo(c)))
+end