Changes between Version 3 and Version 4 of Ticket #28554


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Timestamp:
10/04/19 18:44:24 (2 years ago)
Author:
gh-DeRhamSource
Comment:

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  • Ticket #28554 – Description

    v3 v4  
    1 How is a scalar field implemented which is split into different expressions in one particular chart?
    2 
    3 Take for instance a scalar field `f` on the real line with standard "top" chart `x`, defined via `f(x)=0 for x<-1`, `f(x)=x+1 for -1<=x<0`, `f(x)=1-x for 0<=x<1` and `f(x)=0 for x>=1`. Currently, this is solved by using
    4 {{{
    5 f = M.scalar_field( unit_step(x + 1)*unit_step(1 - x)*(1 - abs(x)) )
    6 }}}
    7 (see https://trac.sagemath.org/ticket/28519#comment:46).
    8 
    9 This solution is quite unhandy and becomes even more so for more complicated scalar fields.
    10 
    11 How is a scalar field implemented which is split into different expressions in one particular chart?
     1How is a scalar field implemented which is piecewisely defined with different expressions in one particular chart?
    122
    133Take for instance a scalar field `f` on the real line with standard "top" chart `x`, defined via `f(x)=0 for x<-1`, `f(x)=x+1 for -1<=x<0`, `f(x)=1-x for 0<=x<1` and `f(x)=0 for x>=1`. Currently, this is solved by using