Re: multiintegral and table

*To*: mathgroup at smc.vnet.net*Subject*: [mg131643] Re: multiintegral and table*From*: Bill Rowe <readnews at sbcglobal.net>*Date*: Sun, 15 Sep 2013 07:07:27 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-outx@smc.vnet.net*Delivered-to*: mathgroup-newsendx@smc.vnet.net

On 9/14/13 at 6:03 AM, phutauruk at gmail.com (Parada Hutauruk) wrote: >Dear all, >I have a function >f_1 [x_,y_] = Integrate[2*y + x^2, {x,0,1},{y,0,x}] Don't do this. f_1 is interpreted by Mathematica as something named f with Head 1 and is definitely not a subscribed variable. You cannot use an underscore in names with Mathematica. Also, did you notice the color of the f when you typed f_2? It wasn't blue (the default color of a undefined global name was it? That should be a big hint you are doing something wrong. getting rid of the underscores: f1[x_, y_] = Integrate[2*y + x^2, {x, 0, 1}, {y, 0, x}]; f2[x_, y_, Q_] = Integrate[2*y + x^2*Q, {x, 0, 1}, {y, 0, x}]; fTotal[x_, y_, Q_] = f1[x, y] + f2[x, y, Q]; dataxx = Table[{Q, fTotal[x, y, Q]}, {Q, 0, 10, 0.0025}]; ListPlot[dataxx] will generate the expected plot. But since both f1 and f2 evaluate to simple expressions and assuming x, y have not been assigned values, then the following code generates the same plot more efficiently f1 = Integrate[2*y + x^2, {x, 0, 1}, {y, 0, x}]; f2 = Integrate[2*y + x^2*Q, {x, 0, 1}, {y, 0, x}]; Plot[f1+f2, {Q, 0, 10}] One other thing. Mathematica has several built-in things that are named with a single uppercase letter. So, it is wise to get in the habit of not using single uppercase letters as variables. That avoids conflict with built-in functions and likely will save you a lot of grief debugging your code.