Massimo2013's profile - activity

Here is a shortened version of what I did in R, and would like to replicate in sagemath:

x=(0:80)/10
meanl=5/3
sdl=2/3
n <- function(z) { 1-plnorm(z,meanlog=meanl,sdlog=sdl) }
b <- function(z) dlnorm(z, meanlog=meanl, sdlog=sdl)
BB <- function(z) integrate(function(w) w * b(w), lower = z, upper = Inf)$value
B <- Vectorize(BB, vectorize.args='z')
h <- function(x) 40*exp(-x)
plot(x,h(x)+x,ylim=c(0,10),type="l")
lines(x,5-x-n(h(x))*h(x)+B(h(x)),xlim=c(0,max(x)),col=3)

Thanks. However, this does not seem to allow me to use N(x) in an expression as I would do with any other (symbolic) function. For example, I'm not even able to 'plot(1-N,(x,0,10))' This is unfortunate, as I wanted to translate into sagemath a simulation I did in R, where I can use "proper" functions, such as 'plnorm' and 'dlnorm'

But what if I need to use it as/in a symbolic function?

I don't understand how to use cumulative distribution functions in sagemath. For example, I'd like to define a function N(x) as N(x)=1-F(x) where F is a cumulative log-normal distribution However, if I try

 W = RealDistribution('lognormal',[1.5,.6])
 N(x) = W.cum_distribution_function(x)

it does not seem to work at all

Is it possible to set the font size for all labels in a plot? I have been able to set the font family changing the internal parameters of matplotlib

from matplotlib import rc
rc('text',usetex=True)
rc('font',**{'family':'serif','serif':['Times']})

I'd like to change the size as well, so that all labels created with 'text' are the same size (note that I want to use TeX in labels)

I've just updated to the 7.3 version of sagemath, and interact does not work under jupyter. Does anybody have the same problem?

Besides, the function g(x) does not seem to be used correctly by solve: solve([g(x)==y,x==4],[x,y]) gives a negative value for y

You are right: it seems to work with plot(g,x,0,10). However, it does not work properly with plot(g(x),x,0,10) Is there something I'm missing about the working of plot?

I need to define a function like the following:

y = 5 - 2x  if f(x)>0
    0       otherwise

I tried different solutions:

f(x) = 5 - 2*x
g(x) = max(f(x),0)

or:

f(x) = 5 - 2*x
def g(x):
     return f(x) if f(x)>0 else 0

However, when I try to plot them, they do not seem to work: the first ignores the lower bound, while the second is always zero. This is strange, as when I try [g(x) for x in range(0,10)] it returns the correct values of g(x)

I'm trying to take advantage of the power of SageMath and the superior efficiency and beauty of Jupyter notebooks. I open locally my notebooks with the command:sagemath -n jupyter. This opens a jupyter notebook with sagemath kernel. However, unfortunately, interaction commands and widgets (slider, select, dropdown) are not fully compatible: under Jupyter I must use ipywidgets, but then the code is not compatible with SageMath, if I want to make it available in SageMathCloud or SageMathCell.

Is there a way to make sagemath @interact commands available to Jupyter? Are there plans to use the same commands and provide a more complete support of SageMath under Jupyter?

I'm working with a function whose functional form is different at a specific value of the parameter (a=1):

 if a==1:
            U(x,L)=log(x)+log(1-L)
 else:
            U(x,L)=(x^(1-a)/(1-a)+(1-L)^(1-a)/(1-a))

Is it possible to define once and for all a function U(x,L,a) which includes the parameter as a variable so that I don't need to redefine it when a = 1?

I'm trying to solve the following system of nonlinear equation:

var("x,L,a")
sms = (x/(1-L))^(1-a) == .3
bb = x == .3*L
solve([sms,bb],x,L)

I expect that sage gives me a symbolic solution, the output is the following:

[x == 0.3*L, (-x/(L - 1))^(-a + 1) == 0.3]

As I am a newbie to sage, I wonder if there's something wrong/missing