Yep, your initial guess doesn't work for $x < 1. I suggest just starting out with 1 instead: 
sub sqrt ($) {
  my $x = shift;
  return sqrt_search( $x, 0, $x, 1, 50);
}

# Tests

sub test
{
    my $n = shift;
    print "SQRT $n: ", &sqrt( $n ), ' ?= ', eval { CORE::sqrt( $n ) } 
+, $/, $/;
}

test( $_ ) for( 16, 9, 4, 2, 0.5, -1, 0, 0.001 );

[download]
Output: 
SQRT 16: 4.0000114440918 ?= 4

SQRT 9: 3 ?= 3

SQRT 4: 1.99998474121094 ?= 2

SQRT 2: 1.4141845703125 ?= 1.4142135623731

SQRT 0.5: 0.7071533203125 ?= 0.707106781186548

SQRT -1:  ?= 

SQRT 0: 0.0078125 ?= 0

SQRT 0.001: 0.03125 ?= 0.0316227766016838

[download]

In reply to Re: [Study]: Searching for square roots by rhesa
in thread [Study]: Searching for square roots by monsieur_champs

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