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2020-05-24 17:24:24 +0200 commented answer Unexpected result for trigonometric function

Sorry, I didn't take a screenshot. But admins can look at the logs.

2020-05-24 05:18:06 +0200 commented answer Unexpected result for trigonometric function

Thanks for the reply. BTW, I was trying to post this question since yesterday, but it was being flagged as spam. Why is that? I am not behind proxy or anything.

2020-05-24 03:39:24 +0200 asked a question Unexpected result for trigonometric function

I'm trying to solve the following trig eqn using sage.

$$sin(x)-cos(x) = 0$$

Hand calculation give me the result of: $$x=\frac{\pi}{4} + n\pi$$

However, the solve() function gives me a different result, why is that?:

sage: 
sage: solve(sin(x)-cos(x) == 0, x, to_poly_solve=True)
[x == 1/4*pi + pi*z25]
sage:

Also, what's z in the answer? I haven't defined any such variable.

2020-05-20 07:57:03 +0200 asked a question How to calculate twos and ones complement?

How can I calculate twos and ones complement in sage?

I tried searching the docs but didn't find anything.

2020-05-09 06:50:16 +0200 commented answer Solving quadratic inequality

Thanks, I didn't notice it.

2020-05-08 19:40:27 +0200 commented answer Solving quadratic inequality

but the answer doesn't contain the last part (2, 6)

2020-05-08 19:31:51 +0200 asked a question Solving quadratic inequality

How to solve the following quadratic inequality:

$$0.3 < \frac{2x}{x^{2} + 4} <0.5$$

The call to solve function return the following output:

sage: 
sage: solve( [(2*x / (4+x**2)) < .5 , (2*x / (x**2 + 4)) > .3 ], x, to_poly_serve=True )
[[-2*x/(x^2 + 4) + 0.5 > 0, 2*x/(x^2 + 4) - 0.3 > 0]]
sage:

By hand calculation I found the following answer $(2/3, 2) \cup (2, 6)$.

2020-04-26 11:53:52 +0200 commented answer How to correctly plot x^(1/3)

So, its a function to plot relations rather than function. Thanks

2020-04-25 19:32:10 +0200 commented answer How to correctly plot x^(1/3)

what's the difference between plot and implicit_plot?

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2020-04-25 17:08:30 +0200 commented answer How to correctly plot x^(1/3)

How you arrive at this function sgn(x)*abs(x)^(1/3)?

2020-04-25 16:03:54 +0200 commented answer How to correctly plot x^(1/3)

Specifying these arguments still doesn't plot the correct graph.

2020-04-25 16:02:09 +0200 commented question How to correctly plot x^(1/3)

I was expecting this

2020-04-25 13:53:08 +0200 asked a question How to correctly plot x^(1/3)

sage: plot(x**(1/3))

This command produces a graph that looks like this:

image

I was expecting a graph like this:

image

2020-04-18 08:19:52 +0200 commented answer Unexpected result in calculating limits

BTW, I don't quite understand the term "complex plane" and how the square root converges to 0. Where I can read more about it?

2020-04-17 13:35:34 +0200 commented answer Unexpected result in calculating limits

is there any way to alter this behavior?

2020-04-15 13:43:24 +0200 asked a question Unexpected result in calculating limits

Limit of sqrt(x-3) when x approaches 3 doesn't exist but the sage returns 0. Why is that?

sage: 
sage: limit(sqrt(x-3), x=3)
0
sage:
2020-04-13 15:20:14 +0200 commented answer Sage returning wrong derivative

Got it thanks :)

2020-04-13 07:05:48 +0200 commented answer Sage returning wrong derivative

exp(1)**(x*y) and exp(x*y) both yields e^(x*y(x)). So, I think my equation is correct. Also, why I need to call the subs method. I used the same procedure to find the derivative of many equations.

2020-04-12 19:25:28 +0200 asked a question Sage returning wrong derivative

I am trying to calculate the derivative of y = e^(x*y)

Hand calculation give me the result of dy/dx = ( y*e^(x*y) ) / ( 1 - x*e^(x*y) )

But the sage is giving me the wrong output of -y/x. Here is my code:

sage: 
sage:  y=function('y')(x)    
sage: y
y(x)
sage: 
sage: expr = exp(1)**(x*y)
sage: 
sage: diff(y)
diff(y(x), x)
sage: 
sage: diff(expr)
(x*diff(y(x), x) + y(x))*e^(x*y(x))
sage: 
sage: solve(diff(expr), diff(y))
[diff(y(x), x) == -y(x)/x]
sage: 
sage:
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2020-03-11 07:24:49 +0200 edited question Calculating inverse of a function

Is there any straightforward way to calculate inverse of a function in sage? For example:

f(x) = 2 * x  - 1
f^-1(x) = ( x + 3 ) / 2

I have encountered solutions like this. But this was answered 9 years ago, I hope there exist a better way to do now.