In Run mode, key two initial estimates into the X- and Y-registers.
Try estimates of 0 and 10 to look for a positive root.
You can now find the desired root by pressing ´_ 0. When you do
this, the calculator will not display the answer right away. The HP-15C uses
an iterative algorithm
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to estimate the root. The algorithm analyzes your
function by sampling it many times, perhaps a dozen times or more. It does
this by repeatedly executing your subroutine. Finding a root will usually
require about 2 to 10 seconds; but sometimes the process will require even
more time.
Press ´_ 0 and sit back while your HP-15C exhibits one of its
powerful capabilities. The display flashes running while _ is
operating.
*
Press ´• 4 to obtain the displays shown here. The display setting does not influence the operation
of _.
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An algorithm is a step-by-step procedure for solving a mathematical problem. An iterative algorithm is one
containing a portion that is executed a number of times in the process of solving the problem.