GUIMath
d2line · d2line_seg · feround · inside

GUIMath

class GUIMath
Syntax:
obj = h.GUIMath()
Description:
Contains functions which calculate common relationships between graphics objects.

GUIMath.d2line()
Syntax:
d = guimath.d2line(xpoint, ypoint, xline0, yline0, xline1, yline1)
Description:
Return distance between the point (xpoint,ypoint) and the (infinitely long) line defined by the 0 and 1 points.

GUIMath.d2line_seg()
Syntax:
d = guimath.d2line_seg(xpoint, ypoint, xline0, yline0, xline1, yline1)
Description:
Return distance between the point (xpoint, ypoint) and the line segment line defined by the 0 and 1 points.

GUIMath.inside()
Syntax:
boolean = guimath.inside(xpoint, ypoint, left, bottom, right, top)
Description:
return 1 if the point is inside the box, 0 otherwise

GUIMath.feround()
Syntax:

mode = guimath.feround()

lastmode = guimath.feround(mode)

Description:

Set the floating point rounding mode. Mode 1, 2, 3, 4 refers to FE_DOWNWARD, FE_TONEAREST, FE_TOWARDZERO, FE_UPWARD respectively. The default, and most accurate, mode is FE_TONEAREST. The mode is changed only if the argument is 1-4. If there is no support for this function the return value is 0.

This function is useful to determine if a simulation depends unduly on double precision round-off error.

This affects calculations performed in both Python and HOC.

Example:

from neuron import h

gm = h.GUIMath()
print 'default rounding mode %d' % gm.feround()

def test_round(mode):
    gm = h.GUIMath()
    old = gm.feround(mode)
    x = 0
    for i in xrange(1, 1000001):
        x += 0.1
    print 'round mode %d x=%25.17lf' % (mode, x)
    gm.feround(old)

for i in xrange(1, 5):
    test_round(i)

Output:

default rounding mode 2
round mode 1 x=  99999.99999613071850035
round mode 2 x= 100000.00000133288267534
round mode 3 x=  99999.99999613071850035
round mode 4 x= 100000.00000432481465396