Context

Table of Contents

This file is written in C because it is more natural to express the context in C than in Fortran.

3 files are produced:

1 Context

The context variable is a handle for the state of the library, and is stored in the following data structure, which can't be seen outside of the library. To simplify compatibility with other languages, the pointer to the internal data structure is converted into a 64-bit signed integer, defined in the qmckl_context type. A value of 0 for the context is equivalent to a NULL pointer.

1.0.1 Source

typedef struct qmckl_context_struct {
  struct qmckl_context_struct * prev;
  uint32_t tag;
  int32_t precision;
  int32_t range;
} qmckl_context_struct;

#define VALID_TAG   0xBEEFFACE
#define INVALID_TAG 0xDEADBEEF

The tag is used internally to check if the memory domain pointed by a pointer is a valid context.

1.1 qmckl_context_check

Checks if the domain pointed by the pointer is a valid context. Returns the input qmckl_context if the context is valid, 0 otherwise.

1.1.1 Header

qmckl_context qmckl_context_check(const qmckl_context context) ;

1.1.2 Source

qmckl_context qmckl_context_check(const qmckl_context context) {

  if (context == (qmckl_context) 0) return (qmckl_context) 0;

  const qmckl_context_struct * ctx = (qmckl_context_struct*) context;

  if (ctx->tag != VALID_TAG) return (qmckl_context) 0;

  return context;
}

1.2 qmckl_context_create

To create a new context, use qmckl_context_create().

  • On success, returns a pointer to a context using the qmckl_context type
  • Returns 0 upon failure to allocate the internal data structure

1.2.1 Header

qmckl_context qmckl_context_create();

1.2.2 Source

qmckl_context qmckl_context_create() {

  qmckl_context_struct* context =
    (qmckl_context_struct*) qmckl_malloc ((qmckl_context) 0, sizeof(qmckl_context_struct));
  if (context == NULL) {
    return (qmckl_context) 0;
  }

  context->prev      = NULL;
  context->precision = QMCKL_DEFAULT_PRECISION;
  context->range     = QMCKL_DEFAULT_RANGE;
  context->tag       = VALID_TAG;

  return (qmckl_context) context;
}

1.2.3 Fortran interface

interface
   integer (c_int64_t) function qmckl_context_create() bind(C)
     use, intrinsic :: iso_c_binding
   end function qmckl_context_create
end interface

1.3 qmckl_context_copy

This function makes a shallow copy of the current context.

  • Copying the 0-valued context returns 0
  • On success, returns a pointer to the new context using the qmckl_context type
  • Returns 0 upon failure to allocate the internal data structure for the new context

1.3.1 Header

qmckl_context qmckl_context_copy(const qmckl_context context);

1.3.2 Source

qmckl_context qmckl_context_copy(const qmckl_context context) {

  const qmckl_context checked_context = qmckl_context_check(context);

  if (checked_context == (qmckl_context) 0) {
    return (qmckl_context) 0;
  }

  qmckl_context_struct* old_context = (qmckl_context_struct*) checked_context;

  qmckl_context_struct* new_context = 
    (qmckl_context_struct*) qmckl_malloc (context, sizeof(qmckl_context_struct));
  if (new_context == NULL) {
    return (qmckl_context) 0;
  }

  new_context->prev      = old_context;
  new_context->precision = old_context->precision;
  new_context->range     = old_context->range;
  new_context->tag       = VALID_TAG;

  return (qmckl_context) new_context;
}

1.3.3 Fortran interface

interface
   integer (c_int64_t) function qmckl_context_copy(context) bind(C)
     use, intrinsic :: iso_c_binding
     integer (c_int64_t), intent(in), value :: context
   end function qmckl_context_copy
end interface

1.4 qmckl_context_previous

Returns the previous context

  • On success, returns the ancestor of the current context
  • Returns 0 for the initial context
  • Returns 0 for the 0-valued context

1.4.1 Header

qmckl_context qmckl_context_previous(const qmckl_context context);

1.4.2 Source

qmckl_context qmckl_context_previous(const qmckl_context context) {

  const qmckl_context checked_context = qmckl_context_check(context);
  if (checked_context == (qmckl_context) 0) {
    return (qmckl_context) 0;
  }

  const qmckl_context_struct* ctx = (qmckl_context_struct*) checked_context;
  return qmckl_context_check((qmckl_context) ctx->prev);
}

1.4.3 Fortran interface

interface
   integer (c_int64_t) function qmckl_context_previous(context) bind(C)
     use, intrinsic :: iso_c_binding
     integer (c_int64_t), intent(in), value :: context
   end function qmckl_context_previous
end interface

1.5 qmckl_context_destroy

Destroys the current context, leaving the ancestors untouched.

  • Succeeds if the current context is properly destroyed
  • Fails otherwise
  • Fails if the 0-valued context is given in argument
  • Fails if the the pointer is not a valid context

1.5.1 Header

qmckl_exit_code qmckl_context_destroy(qmckl_context context);

1.5.2 Source

qmckl_exit_code qmckl_context_destroy(const qmckl_context context) {

  const qmckl_context checked_context = qmckl_context_check(context);
  if (checked_context == (qmckl_context) 0) return QMCKL_FAILURE;

  qmckl_context_struct* ctx = (qmckl_context_struct*) context;
  if (ctx == NULL) return QMCKL_FAILURE;

  ctx->tag = INVALID_TAG;
  qmckl_free(ctx);
  return QMCKL_SUCCESS;
}

1.5.3 Fortran interface

interface
   integer (c_int32_t) function qmckl_context_destroy(context) bind(C)
     use, intrinsic :: iso_c_binding
     integer (c_int64_t), intent(in), value :: context
   end function qmckl_context_destroy
end interface

2 Precision

The following functions set and get the expected required precision and range. precision should be an integer between 2 and 53, and range should be an integer between 2 and 11.

The setter functions functions return a new context as a 64-bit integer. The getter functions return the value, as a 32-bit integer. The update functions return QMCKL_SUCCESS or QMCKL_FAILURE.

2.1 qmckl_context_update_precision

2.1.1 Header

qmckl_exit_code qmckl_context_update_precision(const qmckl_context context, const int precision);

2.1.2 Source

qmckl_exit_code qmckl_context_update_precision(const qmckl_context context, const int precision) {

  if (precision <  2) return QMCKL_FAILURE;
  if (precision > 53) return QMCKL_FAILURE;

  qmckl_context_struct* ctx = (qmckl_context_struct*) context;
  if (ctx == NULL) return QMCKL_FAILURE;

  ctx->precision = precision;
  return QMCKL_SUCCESS;
}

2.1.3 Fortran interface

interface
   integer (c_int32_t) function qmckl_context_update_precision(context, precision) bind(C)
     use, intrinsic :: iso_c_binding
     integer (c_int64_t), intent(in), value :: context
     integer (c_int32_t), intent(in), value :: precision
   end function qmckl_context_update_precision
end interface

2.2 qmckl_context_update_range

2.2.1 Header

qmckl_exit_code qmckl_context_update_range(const qmckl_context context, const int range);

2.2.2 Source

qmckl_exit_code qmckl_context_update_range(const qmckl_context context, const int range) {

  if (range <  2) return QMCKL_FAILURE;
  if (range > 11) return QMCKL_FAILURE;

  qmckl_context_struct* ctx = (qmckl_context_struct*) context;
  if (ctx == NULL) return QMCKL_FAILURE;

  ctx->range = range;
  return QMCKL_SUCCESS;
}

2.2.3 Fortran interface

interface
   integer (c_int32_t) function qmckl_context_update_range(context, range) bind(C)
     use, intrinsic :: iso_c_binding
     integer (c_int64_t), intent(in), value :: context
     integer (c_int32_t), intent(in), value :: range
   end function qmckl_context_update_range
end interface

2.3 qmckl_context_set_precision

2.3.1 Header

qmckl_context qmckl_context_set_precision(const qmckl_context context, const int precision);

2.3.2 Source

qmckl_context qmckl_context_set_precision(const qmckl_context context, const int precision) {
  qmckl_context new_context = qmckl_context_copy(context);
  if (new_context == 0) return 0;

  if (qmckl_context_update_precision(context, precision) == QMCKL_FAILURE) return 0;

  return new_context;
}

2.3.3 Fortran interface

interface
   integer (c_int32_t) function qmckl_context_set_precision(context, precision) bind(C)
     use, intrinsic :: iso_c_binding
     integer (c_int64_t), intent(in), value :: context
     integer (c_int32_t), intent(in), value :: precision
   end function qmckl_context_set_precision
end interface

2.4 qmckl_context_set_range

2.4.1 Header

qmckl_context qmckl_context_set_range(const qmckl_context context, const int range);

2.4.2 Source

qmckl_context qmckl_context_set_range(const qmckl_context context, const int range) {
  qmckl_context new_context = qmckl_context_copy(context);
  if (new_context == 0) return 0;

  if (qmckl_context_update_range(context, range) == QMCKL_FAILURE) return 0;

  return new_context;
}

2.4.3 Fortran interface

interface
   integer (c_int32_t) function qmckl_context_set_range(context, range) bind(C)
     use, intrinsic :: iso_c_binding
     integer (c_int64_t), intent(in), value :: context
     integer (c_int32_t), intent(in), value :: range
   end function qmckl_context_set_range
end interface

2.5 qmckl_context_get_precision

2.5.1 Header

int32_t qmckl_context_get_precision(const qmckl_context context);

2.5.2 Source

int qmckl_context_get_precision(const qmckl_context context) {
  const qmckl_context_struct* ctx = (qmckl_context_struct*) context;
  return ctx->precision;
}

2.5.3 Fortran interface

interface
   integer (c_int32_t) function qmckl_context_get_precision(context) bind(C)
     use, intrinsic :: iso_c_binding
     integer (c_int64_t), intent(in), value :: context
   end function qmckl_context_get_precision
end interface

2.6 qmckl_context_get_range

2.6.1 Header

int32_t qmckl_context_get_range(const qmckl_context context);

2.6.2 Source

int qmckl_context_get_range(const qmckl_context context) {
  const qmckl_context_struct* ctx = (qmckl_context_struct*) context;
  return ctx->range;
}

2.6.3 Fortran interface

interface
   integer (c_int32_t) function qmckl_context_get_range(context) bind(C)
     use, intrinsic :: iso_c_binding
     integer (c_int64_t), intent(in), value :: context
   end function qmckl_context_get_range
end interface

2.7 qmckl_context_get_epsilon

Returns \(\epsilon = 2 / \log_{10} 2^{n-1}\) where n is the precision

2.7.1 Header

double qmckl_context_get_epsilon(const qmckl_context context);

2.7.2 Source

double qmckl_context_get_epsilon(const qmckl_context context) {
  const qmckl_context_struct* ctx = (qmckl_context_struct*) context;
  return 1.0 / ((double) ((int64_t) 1 << (ctx->precision-1)));
}

2.7.3 Fortran interface

interface
   real (c_double) function qmckl_context_get_epsilon(context) bind(C)
     use, intrinsic :: iso_c_binding
     integer (c_int64_t), intent(in), value :: context
   end function qmckl_context_get_epsilon
end interface

3 Info about the molecular system

3.1 TODO qmckl_context_set_nucl_coord

3.2 TODO qmckl_context_set_nucl_charge

3.3 TODO qmckl_context_set_elec_num

Created: 2020-11-04 Wed 23:47

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