onrammp exercise 14.2 stellar motion part 2, task 6 movaway
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For task 6 I don't understand how matlab connects starname to a particular graph.
Also I'm not sure how this piece of code works...
"movaway = starnames(speed < 0) "
how does this line of code use a variable that is in a loop before this line of code?
Sorry in advance if this is an obvious question.
Task 1
[sHa,idx] = min(spectra);
lambdaHa = lambda(idx);
z = lambdaHa/656.28 - 1;
speed = z*299792.458
Tasks 2 - 4
for c = 1:7
s = spectra(:,c);
if speed(c) >= 0
loglog(lambda,s,"--")
else
loglog(lambda,s,"LineWidth",3)
end
hold on
end
hold off
Task 5
legend(starnames)
Task 6
movaway = starnames(speed < 0)
1 Comment
Nikita
on 12 Feb 2024
Add an if statement to the for loop body. If speed(v) is less than or equal to 0, create a plot of s against lambda using a dashed line (--).
Add the command hold on between the two end keywords so that you only create one plot.
Accepted Answer
KALYAN ACHARJYA
on 3 Jan 2020
Edited: KALYAN ACHARJYA
on 3 Jan 2020
See the example, lets suppose starnames is variable having all types of numbers
starnames=[-2 3 45 7 2 0 -4 5 7 7 6 9];
speed=[2 3 -4 5 6 7 8 0 5 2 -30] ; % Just random example
## speed<0 is an conditional assignment, its return a logical array (with 0 & 1), when condition true, its 1, otherwise 0
>> speed < 0
ans =
1×11 logical array
0 0 1 0 0 0 0 0 0 0 1
## starnames(speed < 0) return an array, where the 1 presence in the above logical array
>> movaway = starnames(speed < 0)
movaway =
45 6
This is just an example to understand the issue (This approach is good way for efficient code, conditional & array indexing)
More Answers (2)
Bongani Tavengwa
on 5 Jun 2020
Edited: DGM
on 22 Feb 2023
Task
Add an if statement to the for loop body. If speed(c) is less than or equal to 0, create a loglog plot of s against lambda using a dashed line (--).
After the if statement, add the command hold on so that only one plot is created.
for c = 1:7
s = spectra(:,c);
if speed(c) >= 0
loglog(lambda,s,"--")
else
loglog(lambda,s,"LineWidth",3)
end
hold on
end
please help me where do i go wrong
tania
on 12 Mar 2024
Habiendo creado un script en tiempo real para encontrar el desplazamiento al rojo, puede modificar fácilmente este script para repetir el cálculo con cualquier estrella de la matriz spectra.
ACTIVIDAD
Modifique la sección Tasks 2 & 7 del script para que realice el cálculo del desplazamiento al rojo con la segunda estrella de spectra en lugar de la sexta.
s = spectra(:,2)
[sHa,idx] = min(s)
lambdaHa = lambda(idx)
z = lambdaHa/656,28 - 1
velocidad = z*299792.458
Test Results:
¡Incorrecto!
¿Es s la segunda columna de spectra?
¿Tiene lambdaHa el valor correcto?
¿Tiene speed el valor correcto?
cual es el error ???
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