topic Re: 'catastrophic error' when allocating array values in Intel® Fortran Compiler

'catastrophic error' when allocating array values

Akshay_Siramdas — Sun, 20 Dec 2020 06:08:20 GMT

I'm trying to allocate array value but encountered a catastrophic error while compiling. Here's the function :

function poisson_pressure(P, B, dx, dy) result(P_n) real, intent(in) :: B(:,:), dx, dy real :: P(:,:), norm=1, P_n(nx,ny), norm_t=1e-6 P_n = P do while (norm > norm_t) P(2:nx-1, 2:ny-1) = ((dy**2 * (P_n(3:,2:ny-1)+P_n(1:nx-2,2:ny-1))) & + (dx**2 * (P_n(2:nx-1,3:)+P_n(2:nx-1,1:ny-2))) & - (dx**2 * dy**2 * B(2:nx-1,2:ny-1))) / (2*(dx**2 + dy**2)) P(:, ny-1) = 0 P(1, = P(2, :) P(nx-1, = P(nx-2, !!! Line that throws compilation error P(:, 1) = P(:, 2) norm = l1norm(P, P_n) P_n = P end do return end function poisson_pressure

The program compiles well if I remove the problematic line. I don't understand why this is happening. I've checked declarations, type, shape etc but nothing bad came up. I'm using

ifort -c foo.F90

as compile command.

Re: 'catastrophic error' when allocating array values

mecej4 — Sun, 20 Dec 2020 11:01:29 GMT

The code that you showed is not a proper external function. No compiler will accept it without corrections and without code in a containing scope.

For instance, the variables nx and ny appear to be from a containing outer scope. The line before the "problematic line" is also problematic. It is wrong for l1norm to be implicitly declared with the wrong type. Check the subscript expressions.

If the function is invoked several times, the value of norm at entry will not be 1, and the conditional expression in the DO WHILE statement will probably be evaluated incorrectly.

Your description does not match the code that you posted. Please show the actual code.

Re: 'catastrophic error' when allocating array values

jimdempseyatthecove — Mon, 21 Dec 2020 16:31:53 GMT

mecej4,

In the posted text (program), it appears that the text formatting replace colon, right paren with a non-printing smiley face.

.OR.

the OP copied the file from this forum, and missed the colon, right paren to hidden smiley face.

I am not sure if Past with Fortran formatting still has this problem. Let's see if it does

array(1,:) = 2 ! left side has array(1,: ) without space following :

Jim Dempsey

Re: 'catastrophic error' when allocating array values

Steve_Lionel — Mon, 21 Dec 2020 17:53:19 GMT

I have reported already the tendency of this forum to replace certain common Fortran syntax with invisible emoji (you can see it only in a brief instant of the display of raw HTML when you edit a post.)

Re: 'catastrophic error' when allocating array values

JohnNichols — Mon, 21 Dec 2020 18:10:55 GMT

From me.rice.edu Professor Akin --

program vector_norm ! A simple vector norm program, Fortran 90 version implicit none integer, parameter :: dp = selected_real_kind(14) ! 14 digits integer, parameter :: MAX = 1000; ! Maximum vector size integer n; ! Actual vector size integer i; ! Loop controls real (kind=dp) :: x(MAX) ! The vector real (kind=dp) :: L1_norm, L2_norm; ! Work results print *,"Enter the vector length: "; read *, n; ! User size input print *, n ! Echo size if ( n > MAX ) then ! Check validity stop "Vector size exceeds dimension, ERROR"; ! Abort run end if ! Input vector contents print *,"Enter the vector: "; read *, (x(i), i=1,n) ! Read values L2_norm = sqrt ( sum ( x(:n)*x(:n) )) ! L2 norm L1_norm = sum ( abs(x(:n)) )/n ! L1 norm write (6,'(" The L2 norm of [")',advance='no') ! Print header ! Loop over vector contents, (except last) do i = 1, n-1 write (6, '(f10.4, ",")', advance = 'no') x(i) ! List values end do ! Now last term write (6, '(f10.4, " ] is: ")', advance = 'no') x(n) ! Last value print *, L2_norm, "." ; ! Print L2 print *, "The L1 norm is: ", L1_norm, "." ; ! Print L1 end program vector_norm ! Running with file lab_1.dat; ! 4 ! 3.14159265358979 5 12e1 .645 ! gives ! Enter the vector length: ! 4 ! Enter the vector: ! The L2 norm of [ 3.1416, 5.0000, 120.0000, 0.6450 ] is: 120.146933499. ! The L1 norm is: 32.196648163397448.

- a nice little program

Re: 'catastrophic error' when allocating array values

JohnNichols — Mon, 21 Dec 2020 19:21:13 GMT

Akin's program give the same results in the latest Fortran classic compiler: which is nice to know.

Re: 'catastrophic error' when allocating array values

JohnNichols — Mon, 21 Dec 2020 23:29:34 GMT

L1 norm is just the average length on the positive number line for the independent elements of the vector.

Re: 'catastrophic error' when allocating array values

JohnNichols — Mon, 21 Dec 2020 23:30:13 GMT

Is the L1 norm invariant under a transformation of the base

Re: 'catastrophic error' when allocating array values

JohnNichols — Mon, 21 Dec 2020 23:35:16 GMT

L1 Norm is the sum of the magnitudes of the vectors in a space

Is the Fortran code in error? Because Akins has divided the sum by the number of vectors

Re: 'catastrophic error' when allocating array values

Akshay_Siramdas — Mon, 21 Dec 2020 23:54:35 GMT

It is an internal function. The line before the problematic line had correct closed parentheses but idk why when I posted got removed in formatting. The norm value changes every time `l1norm` is invoked. May I know why repeated calling changes the value of a variable?

The posted code is the actual part of the code!

Re: 'catastrophic error' when allocating array values

JohnNichols — Tue, 22 Dec 2020 04:31:38 GMT

because nx and ny will have strange value if they exist at all.

Re: 'catastrophic error' when allocating array values

JohnNichols — Tue, 22 Dec 2020 04:41:17 GMT

function poisson_pressure(P, B, dx, dy) result(P_n) real, intent(in) :: B(:,:), dx, dy integer :: nx = 100 integer :: ny = 100 real :: P(:,:), norm=1, P_n(100,100), norm_t=1e-6 P_n = P do while (norm > norm_t) P(2:nx-1, 2:ny-1) = ((dy**2 * (P_n(3:,2:ny-1)+P_n(1:nx-2,2:ny-1))) & + (dx**2 * (P_n(2:nx-1,3:)+P_n(2:nx-1,1:ny-2))) & - (dx**2 * dy**2 * B(2:nx-1,2:ny-1))) / (2*(dx**2 + dy**2)) P(:, ny-1) = 0 P(1,:) = P(2, :) P(nx-1,:) = P(nx-2,:) !!! Line that throws compilation error P(:, 1) = P(:, 2) !norm = l1norm(P, P_n) P_n = P end do return end function poisson_pressure

It compiles now - but I need a calling routine, you cannot expect people to do a lot of work. PS it will not compile until nx and ny are defined and P_n should probably be allocatable.

Re: 'catastrophic error' when allocating array values

JohnNichols — Tue, 22 Dec 2020 04:42:09 GMT

also supply an l1norm function

Re: 'catastrophic error' when allocating array values

Akshay_Siramdas — Tue, 22 Dec 2020 04:47:04 GMT

function l1norm(matA, matB) result(norm_r) real, intent(in) :: matA(:,:), matB(:,:) real :: norm_r norm_r = (sum(abs(matA) - abs(matB)))/(sum(abs(matB))) return end function l1norm

This was my 'l1norm' function.

Thanks for the help! I also want to know whether repeated allocation to any array will write garbage values to it?

Re: 'catastrophic error' when allocating array values

andrew_4619 — Tue, 22 Dec 2020 09:47:45 GMT

If you wish norm=1 to be set every time this is called you need it to be set by a runtime statement. Not by a compile time initialisation.

I don't see an allocatables in the sample BTW.

Re: 'catastrophic error' when allocating array values

JohnNichols — Tue, 22 Dec 2020 17:31:34 GMT

ok -- I am more than a little confused.

Where did you get your L1 Norm from -- it is a single number returned from a vector of lengths. The Manhattan Taxi.

And we need a driving program - something that can be tested in a Fortran compiler.

I am not trying to be difficult but you are dealing with busy folk who have a much higher level of knowledge of Fortran than I , but my Pure Maths says -- this is just a little weird without some background.

If you are using the L1 Norm to determine a delta error there are better ways to calculate it I would think.