Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Help Numerical integration in matlab

  1. Jan 6, 2012 #1
    Help!! Numerical integration in matlab

    So (assuming the period in a damped harmonic oscillator is constant, because it is right?)

    I have been asked to find T= 2* (integral from x1 to x2 of(1/v_num)dx) where x1 and x2 are two consecutive extrema (?? not sure what he means with this, i supossed he mean a max and a min, im spanish and my teacher is german, he doesnt speak spanish and all, and his accent makes me hard to understand what he says in english too. He never told us anything about numerical integration)

    where x_num is
    Spoiler:
    76X1
    x_num =

    2.5031
    3.2700
    3.9152
    4.3457
    4.7871
    5.0556
    5.1416
    5.1963
    5.2314
    5.0160
    4.8071
    4.4870
    4.0921
    3.6850
    3.2715
    2.7567
    2.3136
    1.8144
    1.3074
    0.8447
    0.3929
    -0.0224
    -0.4132
    -0.7527
    -1.0654
    -1.3259
    -1.5381
    -1.6895
    -1.8126
    -1.9019
    -1.9227
    -1.9228
    -1.9328
    -1.8343
    -1.7121
    -1.6082
    -1.4477
    -1.2862
    -1.1291
    -0.9619
    -0.7710
    -0.5915
    -0.4040
    -0.2357
    -0.0740
    0.0758
    0.2112
    0.3394
    0.4424
    0.5282
    0.6087
    0.6603
    0.6900
    0.7287
    0.7280
    0.7292
    0.7063
    0.6620
    0.6168
    0.5745
    0.5165
    0.4525
    0.3928
    0.3282
    0.2538
    0.1862
    0.1219
    0.0601
    0.0010
    -0.0522
    -0.1013
    -0.1441
    -0.1818
    -0.2099
    -0.2347
    -0.2515


    or the mid point version 75X1
    x_num_mid =

    2.5031
    3.2700
    3.9152
    4.3457
    4.7871
    5.0556
    5.1416
    5.1963
    5.2314
    5.0160
    4.8071
    4.4870
    4.0921
    3.6850
    3.2715
    2.7567
    2.3136
    1.8144
    1.3074
    0.8447
    0.3929
    -0.0224
    -0.4132
    -0.7527
    -1.0654
    -1.3259
    -1.5381
    -1.6895
    -1.8126
    -1.9019
    -1.9227
    -1.9228
    -1.9328
    -1.8343
    -1.7121
    -1.6082
    -1.4477
    -1.2862
    -1.1291
    -0.9619
    -0.7710
    -0.5915
    -0.4040
    -0.2357
    -0.0740
    0.0758
    0.2112
    0.3394
    0.4424
    0.5282
    0.6087
    0.6603
    0.6900
    0.7287
    0.7280
    0.7292
    0.7063
    0.6620
    0.6168
    0.5745
    0.5165
    0.4525
    0.3928
    0.3282
    0.2538
    0.1862
    0.1219
    0.0601
    0.0010
    -0.0522
    -0.1013
    -0.1441
    -0.1818
    -0.2099
    -0.2347

    and v_num is
    Spoiler:
    75X1
    v_num =

    9.5859
    8.0662
    5.3803
    5.5174
    3.3571
    1.0750
    0.6840
    0.4380
    -2.6924
    -2.6117
    -4.0005
    -4.9371
    -5.0884
    -5.1679
    -6.4351
    -5.5394
    -6.2402
    -6.3369
    -5.7840
    -5.6470
    -5.1912
    -4.8853
    -4.2436
    -3.9096
    -3.2555
    -2.6531
    -1.8917
    -1.5386
    -1.1163
    -0.2611
    -0.0004
    -0.1254
    1.2314
    1.5276
    1.2986
    2.0062
    2.0181
    1.9649
    2.0898
    2.3855
    2.2444
    2.3429
    2.1041
    2.0214
    1.8723
    1.6927
    1.6030
    1.2876
    1.0721
    1.0056
    0.6454
    0.3718
    0.4835
    -0.0095
    0.0153
    -0.2865
    -0.5532
    -0.5645
    -0.5288
    -0.7256
    -0.8005
    -0.7455
    -0.8080
    -0.9298
    -0.8455
    -0.8029
    -0.7731
    -0.7379
    -0.6660
    -0.6139
    -0.5351
    -0.4701
    -0.3518
    -0.3100
    -0.2101

    Ive done integration in matlab before, but never derived from lab data.

    The trouble im having here is that whatever I do, the period I get is about 20-60 secs while looking at x_num and t_num side by side the logical thing would be for it to be 2-5 secs. Been using trapz.
     
  2. jcsd
  3. Jan 8, 2012 #2
    Re: Help!! Numerical integration in matlab

    ok i figured it own alone

    Thanks anyway!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Help Numerical integration in matlab
Loading...