Text backend plotting

[SamLubelsky]

Fixes #26481. For some reason, the bounds of the backend renderer became complex at some point. I just check if they are complex and then convert them to real if the complex part is equal to 0.

This solution is kinda a hack and it might be good to investigate why the endpoints are becoming complex at some point, but this fixes the problem I was having.

Also, might still be a good idea to add in some message telling user that installing matplotlib would probably be a good idea.

References to other Issues or PRs

Brief description of what is fixed or changed

Other comments

Release Notes

• plotting
  • Fixed an issue which caused plotting using backend='text' to error.

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• plotting
  • Fixed an issue which caused plotting using backend='text' to error. (#26484 by @SamLubelsky)

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Fixes #26481.  For some reason, the bounds of the backend renderer became complex at some point.  I just check if they are complex and then convert them to real if the complex part is equal to 0.

This solution is kinda a hack and it might be good to investigate why the endpoints are becoming complex at some point, but this fixes the problem I was having.

Also, might still be a good idea to add in some message telling user that installing matplotlib would probably be a good idea. 

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* plotting
  * Fixed an issue which caused plotting using backend='text' to error.
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Update

The release notes on the wiki have been updated.

[github-actions]

Benchmark results from GitHub Actions

Lower numbers are good, higher numbers are bad. A ratio less than 1
means a speed up and greater than 1 means a slowdown. Green lines
beginning with + are slowdowns (the PR is slower then master or
master is slower than the previous release). Red lines beginning
with - are speedups.

Significantly changed benchmark results (PR vs master)

Significantly changed benchmark results (master vs previous release)

| Change   | Before [2487dbb5]    | After [8b09ff24]    |   Ratio | Benchmark (Parameter)                                                |
|----------|----------------------|---------------------|---------|----------------------------------------------------------------------|
| -        | 69.2±1ms             | 43.8±0.2ms          |    0.63 | integrate.TimeIntegrationRisch02.time_doit(10)                       |
| -        | 67.6±0.3ms           | 43.0±0.3ms          |    0.64 | integrate.TimeIntegrationRisch02.time_doit_risch(10)                 |
| +        | 18.1±0.1μs           | 30.1±0.4μs          |    1.66 | integrate.TimeIntegrationRisch03.time_doit(1)                        |
| -        | 5.36±0.03ms          | 2.93±0.04ms         |    0.55 | logic.LogicSuite.time_load_file                                      |
| -        | 72.2±0.2ms           | 29.2±0.2ms          |    0.4  | polys.TimeGCD_GaussInt.time_op(1, 'dense')                           |
| -        | 25.7±0.1ms           | 17.1±0.05ms         |    0.67 | polys.TimeGCD_GaussInt.time_op(1, 'expr')                            |
| -        | 72.8±0.2ms           | 28.9±0.2ms          |    0.4  | polys.TimeGCD_GaussInt.time_op(1, 'sparse')                          |
| -        | 253±0.8ms            | 124±0.3ms           |    0.49 | polys.TimeGCD_GaussInt.time_op(2, 'dense')                           |
| -        | 255±1ms              | 125±0.3ms           |    0.49 | polys.TimeGCD_GaussInt.time_op(2, 'sparse')                          |
| -        | 655±2ms              | 371±3ms             |    0.57 | polys.TimeGCD_GaussInt.time_op(3, 'dense')                           |
| -        | 655±3ms              | 369±2ms             |    0.56 | polys.TimeGCD_GaussInt.time_op(3, 'sparse')                          |
| -        | 487±2μs              | 285±2μs             |    0.58 | polys.TimeGCD_LinearDenseQuadraticGCD.time_op(1, 'dense')            |
| -        | 1.77±0.01ms          | 1.05±0.01ms         |    0.59 | polys.TimeGCD_LinearDenseQuadraticGCD.time_op(2, 'dense')            |
| -        | 6.33±0.01ms          | 3.11±0.04ms         |    0.49 | polys.TimeGCD_LinearDenseQuadraticGCD.time_op(3, 'dense')            |
| -        | 447±2μs              | 232±3μs             |    0.52 | polys.TimeGCD_QuadraticNonMonicGCD.time_op(1, 'dense')               |
| -        | 1.48±0.02ms          | 678±10μs            |    0.46 | polys.TimeGCD_QuadraticNonMonicGCD.time_op(2, 'dense')               |
| -        | 4.93±0.1ms           | 1.64±0.01ms         |    0.33 | polys.TimeGCD_QuadraticNonMonicGCD.time_op(3, 'dense')               |
| -        | 373±3μs              | 206±0.3μs           |    0.55 | polys.TimeGCD_SparseGCDHighDegree.time_op(1, 'dense')                |
| -        | 2.44±0.02ms          | 1.22±0ms            |    0.5  | polys.TimeGCD_SparseGCDHighDegree.time_op(3, 'dense')                |
| -        | 10.2±0.05ms          | 4.34±0.02ms         |    0.43 | polys.TimeGCD_SparseGCDHighDegree.time_op(5, 'dense')                |
| -        | 360±3μs              | 169±0.9μs           |    0.47 | polys.TimeGCD_SparseNonMonicQuadratic.time_op(1, 'dense')            |
| -        | 2.50±0.01ms          | 884±10μs            |    0.35 | polys.TimeGCD_SparseNonMonicQuadratic.time_op(3, 'dense')            |
| -        | 9.56±0.05ms          | 2.70±0.02ms         |    0.28 | polys.TimeGCD_SparseNonMonicQuadratic.time_op(5, 'dense')            |
| -        | 1.04±0ms             | 423±4μs             |    0.41 | polys.TimePREM_LinearDenseQuadraticGCD.time_op(3, 'dense')           |
| -        | 1.70±0.01ms          | 499±1μs             |    0.29 | polys.TimePREM_LinearDenseQuadraticGCD.time_op(3, 'sparse')          |
| -        | 5.91±0.03ms          | 1.82±0.01ms         |    0.31 | polys.TimePREM_LinearDenseQuadraticGCD.time_op(5, 'dense')           |
| -        | 8.35±0.03ms          | 1.48±0.01ms         |    0.18 | polys.TimePREM_LinearDenseQuadraticGCD.time_op(5, 'sparse')          |
| -        | 283±1μs              | 64.2±0.4μs          |    0.23 | polys.TimePREM_QuadraticNonMonicGCD.time_op(1, 'sparse')             |
| -        | 3.42±0.02ms          | 397±2μs             |    0.12 | polys.TimePREM_QuadraticNonMonicGCD.time_op(3, 'dense')              |
| -        | 3.97±0.02ms          | 274±0.7μs           |    0.07 | polys.TimePREM_QuadraticNonMonicGCD.time_op(3, 'sparse')             |
| -        | 7.08±0.08ms          | 1.28±0.02ms         |    0.18 | polys.TimePREM_QuadraticNonMonicGCD.time_op(5, 'dense')              |
| -        | 8.66±0.09ms          | 826±5μs             |    0.1  | polys.TimePREM_QuadraticNonMonicGCD.time_op(5, 'sparse')             |
| -        | 4.98±0.01ms          | 2.95±0.02ms         |    0.59 | polys.TimeSUBRESULTANTS_LinearDenseQuadraticGCD.time_op(2, 'sparse') |
| -        | 12.1±0.2ms           | 6.72±0.1ms          |    0.56 | polys.TimeSUBRESULTANTS_LinearDenseQuadraticGCD.time_op(3, 'dense')  |
| -        | 22.0±0.2ms           | 9.00±0.03ms         |    0.41 | polys.TimeSUBRESULTANTS_LinearDenseQuadraticGCD.time_op(3, 'sparse') |
| -        | 5.23±0.03ms          | 856±3μs             |    0.16 | polys.TimeSUBRESULTANTS_QuadraticNonMonicGCD.time_op(1, 'sparse')    |
| -        | 12.4±0.03ms          | 7.01±0.08ms         |    0.57 | polys.TimeSUBRESULTANTS_QuadraticNonMonicGCD.time_op(2, 'sparse')    |
| -        | 103±0.8ms            | 25.9±0.1ms          |    0.25 | polys.TimeSUBRESULTANTS_QuadraticNonMonicGCD.time_op(3, 'dense')     |
| -        | 166±0.7ms            | 53.6±0.1ms          |    0.32 | polys.TimeSUBRESULTANTS_QuadraticNonMonicGCD.time_op(3, 'sparse')    |
| -        | 170±0.3μs            | 113±2μs             |    0.66 | polys.TimeSUBRESULTANTS_SparseGCDHighDegree.time_op(1, 'dense')      |
| -        | 362±2μs              | 217±1μs             |    0.6  | polys.TimeSUBRESULTANTS_SparseGCDHighDegree.time_op(1, 'sparse')     |
| -        | 4.31±0.03ms          | 835±7μs             |    0.19 | polys.TimeSUBRESULTANTS_SparseGCDHighDegree.time_op(3, 'dense')      |
| -        | 5.21±0.05ms          | 379±2μs             |    0.07 | polys.TimeSUBRESULTANTS_SparseGCDHighDegree.time_op(3, 'sparse')     |
| -        | 19.8±0.08ms          | 2.79±0.01ms         |    0.14 | polys.TimeSUBRESULTANTS_SparseGCDHighDegree.time_op(5, 'dense')      |
| -        | 22.6±0.1ms           | 617±2μs             |    0.03 | polys.TimeSUBRESULTANTS_SparseGCDHighDegree.time_op(5, 'sparse')     |
| -        | 485±4μs              | 137±2μs             |    0.28 | polys.TimeSUBRESULTANTS_SparseNonMonicQuadratic.time_op(1, 'sparse') |
| -        | 4.74±0.06ms          | 612±1μs             |    0.13 | polys.TimeSUBRESULTANTS_SparseNonMonicQuadratic.time_op(3, 'dense')  |
| -        | 5.32±0.06ms          | 138±1μs             |    0.03 | polys.TimeSUBRESULTANTS_SparseNonMonicQuadratic.time_op(3, 'sparse') |
| -        | 13.8±0.1ms           | 1.27±0ms            |    0.09 | polys.TimeSUBRESULTANTS_SparseNonMonicQuadratic.time_op(5, 'dense')  |
| -        | 13.8±0.2ms           | 141±1μs             |    0.01 | polys.TimeSUBRESULTANTS_SparseNonMonicQuadratic.time_op(5, 'sparse') |
| -        | 137±3μs              | 75.0±1μs            |    0.55 | solve.TimeMatrixOperations.time_rref(3, 0)                           |
| -        | 249±3μs              | 88.5±1μs            |    0.35 | solve.TimeMatrixOperations.time_rref(4, 0)                           |
| -        | 24.2±0.06ms          | 10.2±0.06ms         |    0.42 | solve.TimeSolveLinSys189x49.time_solve_lin_sys                       |
| -        | 28.1±0.3ms           | 15.3±0.09ms         |    0.54 | solve.TimeSparseSystem.time_linsolve_Aaug(20)                        |
| -        | 55.3±0.2ms           | 24.8±0.1ms          |    0.45 | solve.TimeSparseSystem.time_linsolve_Aaug(30)                        |
| -        | 27.9±0.1ms           | 15.2±0.2ms          |    0.55 | solve.TimeSparseSystem.time_linsolve_Ab(20)                          |
| -        | 54.5±0.4ms           | 24.5±0.2ms          |    0.45 | solve.TimeSparseSystem.time_linsolve_Ab(30)                          |

Full benchmark results can be found as artifacts in GitHub Actions
(click on checks at the top of the PR).