Surprising DSolve problem

*To*: mathgroup at smc.vnet.net*Subject*: [mg123944] Surprising DSolve problem*From*: Sam Takoy <sam.takoy at yahoo.com>*Date*: Mon, 2 Jan 2012 02:42:06 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com

Hi, I find that my Mathematica (8.0.1) can do DSolve[ y''[x] + (2 y[x])/(Cosh[x]^2) == 0, y, x] but can't do DSolve[ y''[x] + (2 y[x])/(a^2 Cosh[x/a]^2) == 0, y, x] (*Additional constant "a") If I am not mistaken, the equations are equivalent by a trivial change of variables. What's going on here? Thanks, Sam

**Follow-Ups**:**Re: Surprising DSolve problem***From:*DrMajorBob <btreat1@austin.rr.com>

**Re: Surprising DSolve problem***From:*"Scot T. Martin" <smartin@seas.harvard.edu>

**Re: Surprising DSolve problem***From:*"Brandon D. Batista" <bdbatista@gmail.com>

**Re: Surprising DSolve problem***From:*"Dave Snead" <dsnead6@charter.net>