TotalView Users Guide - CI Wiki

Visualizing Array Data
Visualizing Data Programmatically
The $visualize function lets you visualize data from within eval points and
the Tools > Evaluate Window. Because you can enter more than one
$visualize function within an eval point or Evaluate Window, you can simultaneous
visualize multiple variables.
If you enter the $visualize function in an eval point, TotalView interprets
rather than compiles the expression, which can greatly decrease performance.
See “Defining Eval Points and Conditional Breakpoints” on page 366 for
information about compiled and interpreted expressions.
Using the $visualize function in an eval point lets you animate the changes
that occur in your data, because the Visualizer updates the array’s display
every time TotalView reaches the eval point. Here is this function’s syntax:
$visualize ( array [, slice_string ])
The array argument names the dataset being visualized. The optional
slice_string argument is a quoted string that defines a constant slice expression
that modifies the array parameter’s dataset. In Fortran, you can use
either a single (’) or double-quotation mark ("). You must use a double-quotation
mark if your language is C or C++.
The following examples show how you can use this function. Notice that
the array’s dimension ordering differs between C/C++ and Fortran.
C and C++ $visualize(my_array);
$visualize (my_array,"[::2][10:15]");
$visualize (my_array,"[12][:]");
Fortran $visualize (my_array)
$visualize (my_array,’(11:16,::2)’)
$visualize (my_array,’(:,13)’)
The first example in each programming language group visualizes the entire
array. The second example selects every second element in the array’s
major dimension; it also clips the minor dimension to all elements in the
range. The third example reduces the dataset to a single dimension by
selecting one subarray.
You may need to cast your data so that TotalView knows what the array’s
dimensions are. For example, here is a the C function that passes a twodimensional
array parameter that does not specify the major dimension’s
extent.
void my_procedure (double my_array[][32])
{ /* procedure body */ }
You would need to cast this before TotalView can visualize it. For example:
$visualize (*(double[32][32]*)my_array);
Sometimes, it’s hard to know what to specify. You can quickly refine array
and slice arguments, for example, by entering the $visualize function into
the Tools > Evaluate Dialog Box. When you select the Evaluate button, you
192 Chapter 9: Visualizing Programs and Data