# jmarcellopereira's profile - activity

2016-09-06 23:18:07 +0100 commented answer How to solve ODE y'' - 4y' + y - x = 0 using rk4?

I got a way to solve the differential equation. If wrong please correct;)

To solve this differential equation we must first make a variable substitution to reduce the differential equation for a first order and thus create a system of ODEs. variable change:

w1 = y w2 = y w3 = y '

Thus, deriving the above variables, we have a system of equations of the form:

w1 '= w2 w2 '= f (x, w1, w2) = 4 * w2 + x

desolve_system_rk4([w2, 4*w2 + x ],[w1 , w2], ics = [0,1,0],ivar = x, step = 0.1, end_points = 2)

2016-09-06 19:08:22 +0100 answered a question How to solve ODE y'' - 4y' + y - x = 0 using rk4?

I tryed

 # w = y''
# z = y'

var('x, w, z')

desolve_system_rk4( [w , 4*z + x] , [w,z] , ics = [0,1,0], ivar = x, end_points = 10, step = 0.1)


But does no work correty :(

2016-09-06 03:29:59 +0100 asked a question How to solve ODE y'' - 4y' + y - x = 0 using rk4?

How to solve ODE y''+y''-4y'+x = 0 using rk4?

2016-09-03 16:31:27 +0100 asked a question How to run sagemathcloud dockerw

Hi everybody

How to run smc cloud? I tryed docker run -v ~/smc:/projects -P williamstein/sagemathcloud and occured:

hub.js daemon successfully started node run/hub.js start --host=localhost --database_nodes localhost --port 5000 --proxy_port 5001 --base_url= --single --logfile /smc/src/../logs/hub.log --pidfile /smc/src/../pids/hub.pid hub start --host=localhost --database_nodes localhost --port 5000 --proxy_port 5001 --base_url= --single --logfile /smc/src/../logs/hub.log --pidfile /smc/src/../pids/hub.pid
coffee> 2016-09-03T14:28:36.777Z - debug: ComputeServerClient.constructor: {"db_name":"smc","db_hosts":["localhost"],"dev":false,"single":false,"base_url":""} ComputeServerClient { set_all_quotas: [Function], close_open_unused_projects: [Function], tar_backup_recent: [Function], move: [Function], set_quotas: [Function], vacate_compute_server: [Function], status: [Function], project: [Function], call: [Function], _get_socket: [Function], socket: [Function], remove_from_cache: [Function], assign_host: [Function], _add_server_single: [Function], add_server: [Function], dbg: [Function], _init_compute_servers_feed: [Function], _init_storage_servers_feed: [Function], _init_db: [Function], _base_url: '', _project_cache: {}, _project_cache_cb: {}, _dev: false, _single: false } coffee> 2016-09-03T14:28:36.804Z - debug: warning: no password file -- will only work if there is no password set. 2016-09-03T14:28:38.296Z - debug: creating 1 connections 2016-09-03T14:28:38.296Z - debug: created 0 connections so far 2016-09-03T14:28:38.297Z - debug: RethinkDB._connect: connecting to localhost... 2016-09-03T14:28:38.306Z - debug: RethinkDB._connect: successfully connected to localhost 2016-09-03T14:28:38.307Z - debug: RethinkDB._connect: connecting to localhost... 2016-09-03T14:28:38.309Z - debug: RethinkDB._connect: successfully connected to localhost 2016-09-03T14:28:38.309Z - debug: finished creating 1 2016-09-03T14:28:38.311Z - debug: RethinkDB._update_pool: undefined 2016-09-03T14:28:38.312Z - debug: [1 concurrent] rethink: query -- 'r.dbList()' 2016-09-03T14:28:38.314Z - debug: [0 concurrent] [0 modified] rethink: query time using (27759db7-9fcb-4487-a13d-3397d9eec499) took 3ms; average=3ms; -- 'r.dbList()' 2016-09-03T14:28:40.182Z - debug: successfully initialized database 2016-09-03T14:28:40.184Z - debug: SyncTable(table='storage_servers',id='b0de7c49').constructor: query=r.db("smc").table("storage_servers", {"readMode": "outdated"}) 2016-09-03T14:28:40.184Z - debug: SyncTable(table='storage_servers',id='b0de7c49').constructor: initializing changefeed 2016-09-03T14:28:40.185Z - debug: SyncTable(table='storage_servers',id='b0de7c49')._init_db: undefined 2016-09-03T14:28:40.185Z - debug: SyncTable(table='storage_servers',id='b0de7c49')._init_db: create the changefeed 2016-09-03T14:28:40.185Z - debug: SyncTable(table='storage_servers',id='b0de7c49')._init_changefeed: undefined 2016-09-03T14:28:40.186Z - debug: SyncTable(table='storage_servers',id='b0de7c49')._init_changefeed: trying to initialize changefeed 2016-09-03T14:28:40.186Z - debug: RethinkDB._update_pool: undefined 2016-09-03T14:28:40.186Z - debug: [1 concurrent] rethink: query -- 'r.db("smc").table("storage_servers", {"readMode": "outdated"}).changes({"includeInitial": false, "includeStates": false})' 2016-09-03T14:28:40.187Z - debug: SyncTable(table='compute_servers',id='9731ba55').constructor: query=r.db("smc").table("compute_servers", {"readMode": "outdated"}) 2016-09-03T14:28:40.187Z - debug: SyncTable(table='compute_servers',id='9731ba55').constructor: initializing changefeed 2016-09-03T14:28:40.188Z - debug: SyncTable(table='compute_servers',id='9731ba55')._init_db: undefined 2016-09-03T14:28:40.188Z - debug: SyncTable(table='compute_servers',id='9731ba55')._init_db: create the changefeed 2016-09-03T14:28:40.188Z - debug: SyncTable(table='compute_servers',id='9731ba55')._init_changefeed: undefined 2016-09-03T14:28:40.188Z - debug: SyncTable(table='compute_servers',id='9731ba55')._init_changefeed: trying to initialize changefeed 2016-09-03T14:28:40.188Z - debug: RethinkDB._update_pool: undefined 2016-09-03T14:28:40.188Z - debug: [2 concurrent] rethink: query -- 'r.db("smc").table("compute_servers", {"readMode": "outdated"}).changes({"includeInitial": false, "includeStates": false ...

2016-05-16 04:45:55 +0100 asked a question How to install seaborn in sagemath cloud?

How to install seaborn in sagemath cloud?

2016-03-20 19:37:23 +0100 answered a question sage 7 installation failed through ppa on ubuntu 14.04

I got this: in SageMath folder ( uncompressed )

 $Sudo ./sage  wait compile and then delete the " .sage " folder in /home/user. $ ./sage

2016-02-22 05:17:23 +0100 commented answer Double Integral

hi, willmwade how to discovery the function of item [0]?

2016-02-22 04:34:44 +0100 answered a question Failure to Connect to Web Server

let try:

open terminal virtual machine and type:

   $ifconfig  copy the ip after, type: $ sage

sage: notebook(interface=' ')


in firefox, by host machine, use: ip_virtual_machine:8080

2016-02-22 04:22:49 +0100 asked a question How to numerical double integral?

How to numerical double integral?

2016-02-12 15:33:06 +0100 commented question Why the Maxima worksheets is not rendering latex / MathJax?

when I use the worksheet to evaluate sagemath sage code, the result is better presented on the screen (here will not be shown). In Maxima the code result leaves unformatted.

2016-02-12 15:24:08 +0100 commented question how to user a external program to plot graphic?

I really want to see the graphics out of sagemath, in another window (ex: gnuplot.plot3d (f = 'cos (x) + sin (y) * 2', xmin = -1, xmax = 1, ymin = -1, ymax = 1, -1 = zmin, zmax = 1, title = None, samples = 25 = 20 isosamples, xlabel = x, ylabel = 'y', interact = True)). Is okay only the first visualization, then does not work. I could not see 2d.

2016-02-12 15:23:44 +0100 answered a question how to user a external program to plot graphic?

I really want to see the graphics out of sagemath, in another window (ex: gnuplot.plot3d (f = 'cos (x) + sin (y) * 2', xmin = -1, xmax = 1, ymin = -1, ymax = 1, -1 = zmin, zmax = 1, title = None, samples = 25 = 20 isosamples, xlabel = x, ylabel = 'y', interact = True)). Is okay only the first visualization, then does not work. I could not see 2d.

2016-02-09 04:10:44 +0100 commented answer How to import the file "function.py" to worksheet sage? sagemath loaded by virtual machine (VirtualBox)

Hi

I solved the problem I created the file function fiboR_SG.py below

def fiboR_SG(n):

if n < 2:

return n

else:

return fiboR_SG(n-1) + fiboR_SG(n-2)


fiboR_SG. fiboR_SG(10)

55


OK :)

2016-02-09 04:10:22 +0100 answered a question How to import the file "function.py" to worksheet sage? sagemath loaded by virtual machine (VirtualBox)

Hi

I solved the problem I created the file function fiboR_SG.py below

def fiboR_SG(n) :
if n < 2:
return n
else:
return fiboR_SG(n-1) + fiboR_SG(n-2)


fiboR_SG. fiboR_SG(10)
55


OK :)

2016-02-08 01:00:19 +0100 commented answer how do I install an spkg?

I tryed, but: make: * No rule to make target 'all-toolchain'. Stop. how to solve?

2016-02-07 15:26:07 +0100 commented answer How to import the file "function.py" to worksheet sage? sagemath loaded by virtual machine (VirtualBox)

Hello tmolteil

my files are on the local machine and the sagemath runs on the virtual machine. I tried that way, but only import virtual machine files, not the host machine.

2016-02-06 21:12:15 +0100 asked a question How to import the file "function.py" to worksheet sage? sagemath loaded by virtual machine (VirtualBox)

i want to import a file function called "function.py" to my Worksheet. How to do?

2016-02-04 20:32:43 +0100 asked a question how to user a external program to plot graphic?

how to user a external program to plot graphic? ex: gnuplot, xmaxima, mgnuplot....

2016-02-04 20:10:41 +0100 asked a question Why the Maxima worksheets is not rendering latex / MathJax?

I use Maxima with sagemath and do not know why the results are not rendered

sage: f(x):=x^2
f(x):=x^2
sage: integrate(f(x),x)
x^3/3

2016-01-24 00:01:28 +0100 asked a question how to add julia sage notebook?

how to add julia in sagemath notebook?

2016-01-05 03:49:14 +0100 commented answer curve fitting coefficients.

## marked ;)

2016-01-05 03:47:21 +0100 marked best answer curve fitting coefficients.

get the model coefficients, but I can not use them to plot the graph. How to solve?

see the code:

dados = [(0, -0.183440428023042),
(0.200000000000000, -0.131101157495126),
(0.400000000000000, 0.0268875670852843),
(0.800000000000000, 0.110532679260319),
(1.00000000000000, 0.253944632998395),
(1.20000000000000, 0.257190123748649),
(1.40000000000000, 0.531888837111346),
(1.60000000000000, 0.579048247883555),
(2.00000000000000, 0.935180993484717),
(2.20000000000000, 0.916600344376623),
(2.60000000000000, 1.13328608090532),
(2.80000000000000, 1.26893326843583),
(3.00000000000000, 1.10202945535186),
(3.40000000000000, 1.13391615491257)]