## #math - Wed 16 May 2007 between 00:40 and 00:54

### NY Lost Funds

 andrew123 can anyone integrate using substitution: sin[(sqrt)x] / (sqrt)x Safrole u = sqrt(x), so du = 1/(2sqrt(x)) dx Copter2 looks like a sin there though :o Safrole thus we get int( sin(sqrt(x))/sqrt(x) dx ) = 2*int( sin(u) du )= -2cos(u) = -2cos(sqrt(x)) TheBlueWizard equivalently, x = u^2, dx = 2 u du, and then substituting is pretty straightforward [n01d] hi guys, whats the function/algorithm to calcalculate sine? andrew123 safrole: if u = sqrt(x) wudnt we get sinu/u du Safrole if u = sqrt(x) then du = 1/(2sqrt(x))du = 1/(2sqrt(x)) dx, sorryso then 2 du = 1/sqrt(x) dxso then we get int( sin(sqrt(x))/sqrt(x) dx ) = int( sin(u) du )= 2*int( sin(u) du )sorryI forgot the 2 andrew123 but we are integrating in regards to u.. so dont we need du/dx = 1/2sqrt(x) then dx = 2sqrt(x).du Safrole andrew you're mixing things here that need nod be mixedwe want a substitution for 1/sqrt(x) dxI found one bsmntbombdood is >, < defined on C? Safrole < . > you mean?An inner product? [n01d] can someone help me whats the manual to solve sine. not using calculator bsmntbombdood no, greater/less than Safrole C is *not* an ordered field Eclipsor [n01d]: ? Safrole you can impose a so called lexicographical order Eclipsor solve sine in what way Safrole but that still has some nuancesBut in general, no > and < are not defined for C shinygerbil [n01d]: do you mean like the Taylor series of sin(x)? bsmntbombdood ok Safrole the Taylor series would require knowledge of cosine shinygerbil hehe, true Safrole that's kind of circular. bsmntbombdood Safrole: no it wouldn't shinygerbil no, waitwell, kinda bsmntbombdood cos(0) is easy to find shinygerbil actually doing a Taylor expansion on sin(x) would