Wrong norm result in generated C code for MATLAB Function block (Simulink R2024b)

I’m using MATLAB R2024b and Simulink R2024b ( 24.2.0.2863752 (R2024b) Update 5). In a MATLAB Function block I compute the Euclidean norm of a 3×1 vector:

function thrustArray = setupPhasing_inSimulink(timeVec, dv, t, m_full, thr, Ts)

thrustArray = zeros(3, length(timeVec));
if length(dv)/3 ~= length(t)
    error('Length of the time and dv are not matched.');
else
    n_burns = length(t);
end

m_before = m_full;
for i = 1:n_burns
    dv_burn = dv((i-1)*3+1:i*3);
    m_after = m_before/exp(norm(dv_burn)/thr.ve);
    debug_norm_dv=norm(dv_burn);

  ...
end
end

When i run the Simulink and add the breakpoint I see following. The value of the dv_burn is following

dv_burn =
-0.02009
0.29035
-0.006347

When the break point hit and i ran to see what is the norm of the dv than i see

debug>> norm(dv_burn)

ans =

0.29111340575281

But when I look at the debug_norm_dv i should have see the same number but instead i see following

debug>> norm(dv_burn)

ans =

0.29111340575281

debug>> debug_norm_dv

debug_norm_dv =

4

debug>> 

For me this gives me a clue that there might be something wrong with the compilation. I am running the model in Accelator mode.

adding some snippets of generated code I do not know if this helps.

  c7_d2 = c7_norm(chartInstance, c7_dv_burn_data, c7_dv_burn_size);
    c7_burn_size[0] = c7_b_size[0];
    c7_d_loop_ub = c7_b_size[0] - 1;
    for (c7_i9 = 0; c7_i9 <= c7_d_loop_ub; c7_i9++) {
      c7_burn_data[c7_i9] = c7_b_data[c7_i9] / c7_d2;
    }



tatic real_T c7_norm(SFc7_Copy_of_simOrbitControlInstanceStruct *chartInstance,
                      real_T c7_x_data[], int32_T c7_x_size[1])
{
  ptrdiff_t c7_incx_t;
  ptrdiff_t c7_n_t;
  real_T c7_c_y;
  int32_T c7_b_n;
  int32_T c7_c_n;
  int32_T c7_n;
  int32_T c7_nx;
  int32_T c7_var;
  (void)chartInstance;
  if (c7_x_size[0] == 0) {
    c7_c_y = 0.0;
  } else {
    c7_nx = c7_x_size[0];
    c7_n = c7_nx;
    c7_b_n = c7_n;
    c7_c_n = c7_b_n;
    c7_var = c7_c_n;
    c7_n_t = (ptrdiff_t)c7_var;
    c7_incx_t = (ptrdiff_t)1;
    c7_c_y = dnrm2(&c7_n_t, &c7_x_data[0], &c7_incx_t);
  }
  return c7_c_y;
}

If any of you would have some ideas please let me know, thank you very much !

[Juraj]

This issue occurs also when i use Update 6

[Adarsh]

Hi @Juraj, Can you please provide the line where you have set the breakpoint?

Also, once try to run the same code using normal mode and verify with the exact steps using the debugger to findout whether the problem is with the generated code or not.