pi(3) [php man page]

PI(3)									 1								     PI(3)

pi - Get value of pi

SYNOPSIS

       float pi (void  )

DESCRIPTION

	Returns  an  approximation  of	pi.  The returned float has a precision based on the precision directive in php.ini, which defaults to 14.
       Also, you can use the M_PI constant which yields identical results to pi(3).

RETURN VALUES

	The value of pi as float.

EXAMPLES

       Example #1

	      pi(3) example

	      <?php
	      echo pi(); // 3.1415926535898
	      echo M_PI; // 3.1415926535898
	      ?>

PHP Documentation Group 														     PI(3)

CAIRO_ARC(3)								 1							      CAIRO_ARC(3)

CairoContext::arc - Adds a circular arc

       Object oriented style (method):

SYNOPSIS

       public void CairoContext::arc (float  $x, float	$y, float  $radius, float  $angle1, float  $angle2)

DESCRIPTION

       Procedural style:
       void cairo_arc (CairoContext  $context, float  $x, float  $y, float  $radius, float  $angle1, float  $angle2)

	Adds a circular arc of the given radius to the current path. The arc is centered at ($x, $y), begins at $angle1 and proceeds in the direc-
       tion of increasing angles to end at $angle2. If $angle2 is less than $angle1 it will be progressively  increased  by  2*M_PI  until  it	is
       greater	than  $angle1.	If there is a current point, an initial line segment will be added to the path to connect the current point to the
       beginning of the arc.  If  this	initial  line  is  undesired,  it  can	be  avoided  by  calling  CairoContext::newSubPath  or	procedural
       cairo_new_sub_path(3) before calling CairoContext::arc or cairo_arc(3). Angles are measured in radians. An angle of 0.0 is in the direction
       of the positive X axis (in user space). An angle of M_PI/2.0 radians (90 degrees) is in the direction of  the  positive	Y  axis  (in  user
       space).	Angles	increase  in the direction from the positive X axis toward the positive Y axis. So with the default transformation matrix,
       angles increase in a clockwise direction. (To convert from degrees to radians, use degrees * (M_PI / 180.).) This function gives the arc in
       the  direction  of  increasing angles; see CairoContext::arcNegative or cairo_arc_negative(3) to get the arc in the direction of decreasing
       angles.

PARAMETERS

	      o $context
		- A valid CairoContext object

	      o $x
		- x position

	      o $y
		- y position

	      o $radius
		- Radius of the arc

	      o $angle1
		- start angle

	      o $angle2
		- end angle

RETURN VALUES

	No value is returned.

EXAMPLES

       Example #1

	      Object oriented style

	      <?php

	      $s = new CairoImageSurface(CairoFormat::ARGB32, 100, 100);
	      $c = new CairoContext($s);

	      $c->setSourceRgb(0, 0, 0);
	      $c->paint();

	      $c->setLineWidth(1);
	      $c->setSourceRgb(1, 1, 1);

	      for ($r = 50; $r > 0; $r -= 10) {
	       $c->arc(50, 50, $r, 0, 2 * M_PI);
	       $c->stroke();
	       $c->fill();
	      }

	      $s->writeToPng(dirname(__FILE__) . '/CairoContext__arc.png');
	      ?>

       Example #2

	      Procedural style

	      <?php

	      $s = cairo_image_surface_create(CAIRO_SURFACE_TYPE_IMAGE, 100, 100);
	      $c = cairo_create($s);

	      cairo_set_source_rgb($c, 0, 0, 0);
	      cairo_paint($c);

	      cairo_set_source_rgb($c, 1, 1, 1);
	      cairo_set_line_width($c, 1);

	      for ($r = 50; $r > 0; $r -= 10) {
	       cairo_arc($c, 50, 50, $r, 0, 2 * M_PI);
	       cairo_stroke($c);
	       cairo_fill($c);
	      }

	      cairo_surface_write_to_png($s, dirname(__FILE__) . '/cairo_arc.png');
	      ?>

SEE ALSO

       CairoContext::arcNegative.

PHP Documentation Group 													      CAIRO_ARC(3)