Constant for machine precision

[ivan-pi]

The code below

pdecheb/pdecheb/inichb.f

Lines 268 to 279 in f429435

	C
	C CALCULATE ROUGH ESTIMATE OF UNIT ROUND-OFF ERROR FOR CHECKING
	C
	TWOU = 0.1D0
	40 TEMP = 1.0D0 + TWOU
	IF (1.0D0.EQ.TEMP) THEN
	TWOU = TWOU*2.0D0
	ELSE
	TWOU = TWOU*0.5D0
	GO TO 40
	END IF
	C

can be replaced with a call to the intrinsic function epsilon:

twou = epsilon(1.0D0)

This could also become a parameter instead of a dynamic variable in a common block.