NIntegrate that upper limit is infinite

*To*: mathgroup at smc.vnet.net*Subject*: [mg71869] NIntegrate that upper limit is infinite*From*: "Evanescence" <origine26 at yahoo.com.tw>*Date*: Fri, 1 Dec 2006 06:22:27 -0500 (EST)

Dear all: My question is as follows: First I definite a function that is: G[a_]=((-(a-Cos[0.5])^(-3/2))/(3*(10)^2))*(Sin[0.5])^(2)+(1/1-0.1*0.1)*(-(0.005*(1+Cos[0.5])+0.001/1000)*(1+Cos[0.5])^(1/2)*(ArcTan[(a-Cos[0.5])^(1/2)/-(1+Cos[0.5])^(1/2)]-Pi/2)+(0.005*(1-Cos[0.5])-0.001/1000)*(1-Cos[0.5])^(1/2)*(-ArcTanh[(1-Cos[0.5])^(1/2)/(a-Cos[0.5])^(1/2)]) another function is: P[a_]=Re[N[LegendreP[(-1/2)+i,a]]] where i =(-1)^(1/2) then NIntegrate[G[a]*P[a],{a,1,infinite}] but get the error message such that I do not get the correct answer so,please solve my confuse,thank you! Evanescence 2006/12/1