user: What is the c source code of the assembly code below?

```asm
<regress_ch>:
  endbr64
  push   %r15
  xor    %eax,%eax
  mov    %r8d,%r15d
  push   %r14
  lea    0x1(%r8),%r14d
  push   %r13
  push   %r12
  mov    %rsi,%r12
  mov    %r14d,%esi
  push   %rbp
  mov    %ecx,%ebp
  mov    %r14d,%ecx
  push   %rbx
  mov    %rdi,%rbx
  mov    $0x1,%edi
  sub    $0x38,%rsp
  mov    %rdx,0x20(%rsp)
  mov    $0x1,%edx
  call   <matrix@plt>
  mov    %r14d,%esi
  mov    $0x1,%edi
  cltq
  mov    %rax,0x8(%rsp)
  xor    %eax,%eax
  call   <vector@plt>
  mov    %r14d,%esi
  mov    $0x1,%edi
  cltq
  mov    %rax,0x10(%rsp)
  xor    %eax,%eax
  call   <vector@plt>
  movslq %eax,%r13
  test   %r14d,%r14d
  jle    L57
  mov    0x8(%rsp),%rax
  mov    %r14d,0x2c(%rsp)
  mov    $0x1,%r10d
  pxor   %xmm2,%xmm2
  lea    0x8(%rax),%r11
  mov    %r15d,%eax
  lea    0x2(%rax),%rcx
  lea    -0x1(%rbp),%eax
  mov    %rax,0x18(%rsp)
  lea    0x10(%rbx,%rax,8),%rdi
  mov    %rcx,%r14
  nopl   0x0(%rax)
L52:
  mov    (%r11),%r9
  lea    0x0(,%r10,4),%rsi
  mov    %r10,%r8
  cs nopw 0x0(%rax,%rax,1)
L11:
  lea    0x0(,%r8,4),%rcx
  lea    0x8(%rbx),%rax
  movaps %xmm2,%xmm1
  test   %ebp,%ebp
  jle    L47
  nopl   0x0(%rax,%rax,1)
L18:
  mov    (%rax),%rdx
  add    $0x8,%rax
  movss  (%rdx,%rcx,1),%xmm0
  mulss  (%rdx,%rsi,1),%xmm0
  addss  %xmm0,%xmm1
  cmp    %rax,%rdi
  jne    L18
L47:
  movss  %xmm1,(%r9,%r8,4)
  add    $0x1,%r8
  lea    -0x1(%r8),%eax
  cmp    %r15d,%eax
  jle    L11
  add    $0x1,%r10
  add    $0x8,%r11
  cmp    %r14,%r10
  jne    L52
  mov    0x18(%rsp),%rsi
  mov    0x2c(%rsp),%r14d
  shl    $0x2,%r10
  mov    $0x4,%ecx
  add    $0x2,%rsi
  nopl   0x0(%rax)
L3:
  mov    $0x1,%eax
  movaps %xmm2,%xmm1
  test   %ebp,%ebp
  jle    L75
  nopl   0x0(%rax)
L15:
  mov    (%rbx,%rax,8),%rdx
  movss  (%rdx,%rcx,1),%xmm0
  mulss  (%r12,%rax,4),%xmm0
  add    $0x1,%rax
  addss  %xmm0,%xmm1
  cmp    %rax,%rsi
  jne    L15
L75:
  movss  %xmm1,0x0(%r13,%rcx,1)
  add    $0x4,%rcx
  cmp    %rcx,%r10
  jne    L3
L57:
  mov    0x10(%rsp),%r15
  mov    0x8(%rsp),%rbx
  mov    %r14d,%esi
  xor    %eax,%eax
  mov    %r15,%rdx
  mov    %rbx,%rdi
  call   <choldc_e@plt>
  mov    0x20(%rsp),%r8
  mov    %r13,%rcx
  mov    %r15,%rdx
  mov    %r14d,%esi
  mov    %rbx,%rdi
  xor    %eax,%eax
  call   <cholsl@plt>
  mov    %r14d,%r8d
  mov    %r14d,%edx
  mov    %rbx,%rdi
  mov    $0x1,%ecx
  mov    $0x1,%esi
  xor    %eax,%eax
  call   <free_matrix@plt>
  mov    %r14d,%edx
  mov    %r15,%rdi
  mov    $0x1,%esi
  xor    %eax,%eax
  call   <free_vector@plt>
  add    $0x38,%rsp
  mov    %r14d,%edx
  mov    %r13,%rdi
  pop    %rbx
  mov    $0x1,%esi
  pop    %rbp
  xor    %eax,%eax
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  jmp    10c0 <free_vector@plt>
```

assistant: ```c
void regress_ch(data, b, a, ndata, ivar) float **data, *a, *b;
int ndata, ivar;
{
  int p = ivar + 1, j, i, k;
  float **d, sum, *diag, *atb;
  d = matrix(1, p, 1, p);
  diag = vector(1, p);
  atb = vector(1, p);
  for (i = 1; i <= p; i++)
    for (j = i; j <= p; j++) {
      sum = 0;
      for (k = 1; k <= ndata; k++)
        sum += data[k][j] * data[k][i];
      d[i][j] = sum;
    }
  for (i = 1; i <= p; i++) {
    sum = 0;
    for (k = 1; k <= ndata; k++)
      sum += data[k][i] * b[k];
    atb[i] = sum;
  }
  choldc_e(d, p, diag);
  cholsl(d, p, diag, atb, a);
  free_matrix(d, 1, p, 1, p);
  free_vector(diag, 1, p);
  free_vector(atb, 1, p);
}
```