bad_roundoff.c running 

h4 should be 0.0001, is  0.00010000000000000, 10000*h4=  1.00000000000000022 
                         h0001 * 10000  should be 1,  =  1.00000000000000000 

abad  should be 8, is  7.99999999999469402 
agood should be 8, is  8.00000000000000000 

abad*abad+abad*abad    128, is  127.99999999983020871 
agood*agood+agood*agood     is  128.00000000000000000