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 True if the point is inside the box, False 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 range(1, 1000001):
x += 0.1
print('round mode %d x=%25.17lf' % (mode, x))
gm.feround(old)

for i in range(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
```