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solve and calculate

asked 2012-01-26 12:21:21 -0500

Mebus gravatar image

How can I solave an equation like x+z^2=1 and then calculate x with z=3 from the solution?

Thanks.

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Shashank gravatar imageShashank ( 2012-01-26 12:58:28 -0500 )edit

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answered 2012-01-26 12:56:53 -0500

Shashank gravatar image
z=var('z')
solve(x+z^2==1,x)[0].substitute(z==3)
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This works, but is there also a more comfortable way to write this: solve(energiebilanz, h51x)[0].substitute(c_luft=12*m/s, mw=(1/3600)*kg/s, hw=146.68*J/g, TL=313*K)

Mebus gravatar imageMebus ( 2012-01-26 20:31:40 -0500 )edit

This works, but is there also a more comfortable way to write this: solve(energiebilanz, h51x)[0].substitute(c_luft=12*m/s, mw=(1/3600)*kg/s, hw=146.68*J/g, TL=313*K) maybe like in a set of parameters? Thanks.

Mebus gravatar imageMebus ( 2012-01-26 20:31:40 -0500 )edit
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answered 2012-01-26 18:25:54 -0500

A variation on the Shashank'answer :

sage: z=var('z')
sage: f(z)=solve(x+z^2==1,x)[0].rhs()
sage: f
z |--> -z^2 + 1
sage: f.diff(z)
z |--> -2*z
sage: f.plot()

Here you consider the function "solution of the equation as function of z", and you do whatever with it.

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Asked: 2012-01-26 12:21:21 -0500

Seen: 122 times

Last updated: Jan 26 '12