Question

我想打印每个t + dt方程组的解的执行时间，其中dt是.01秒

import { Button, Text, View } from 'react-native';

class HomeScreen extends React.Component {
  render() {
    return (
      <View style={{ flex: 1, justifyContent: 'center', alignItems: 'center' }}>
        <Text>Home!</Text>
        <Button
          title="Go to Settings"
          onPress={() => this.props.navigation.navigate('Settings')}
        />
      </View>
    );
  }
}

class SettingsScreen extends React.Component {
  render() {
    return (
      <View style={{ flex: 1, justifyContent: 'center', alignItems: 'center' }}>
        <Text>Settings!</Text>
        <Button
          title="Go to Home"
          onPress={() => this.props.navigation.navigate('Home')}
        />
      </View>
    );
  }
}

由于我的时间间隔是.01（10/1000），从技术上讲，我应该有1000行输出语句，但由于某种原因，打印的行数要少得多。这根据设定的初始条件而变化。对于[0,0]，大约打印10行。对于[1,2]，大约有400行打印。我不明白为什么会这样。

Answer 1

您正在做一些奇怪的事情，您正在测量ODE功能的执行时间。由于您的少数算术运算需要大约100个，最多几个1000个时钟周期，并且您的处理器每秒工作10 ^ 9个时钟周期，您的调用大约需要1到6秒，这在给定的输出格式中是看不到的。您有时会看到一些解释器开销和JIT编译时间。

odeint使用内部自适应步长，请求的输出从内部步骤进行插值。内部步长可以小于输入时间阵列的时间步长，或者在诸如常数解决方案的钻孔解决方案的情况下，它可以非常大。 ODE功能仅在内部步骤调用，而不是在所有请求的输出时间调用。如果您将t和z添加到打印值，您会看到。

(0.0, array([ 0.,  0.]), 'Execution took: 0:00:00.000010 secs (Wall clock time)')
(1.221926641140105e-06, array([ 0.,  0.]), 'Execution took: 0:00:00 secs (Wall clock time)')
(2.44385328228021e-06, array([ 0.,  0.]), 'Execution took: 0:00:00.000010 secs (Wall clock time)')
(0.01222171026468333, array([ 0.,  0.]), 'Execution took: 0:00:00.000010 secs (Wall clock time)')
(0.02444097667608438, array([ 0.,  0.]), 'Execution took: 0:00:00.000010 secs (Wall clock time)')
(0.03666024308748543, array([ 0.,  0.]), 'Execution took: 0:00:00.000010 secs (Wall clock time)')
(0.15885290720149592, array([ 0.,  0.]), 'Execution took: 0:00:00.000010 secs (Wall clock time)')
(0.28104557131550645, array([ 0.,  0.]), 'Execution took: 0:00:00 secs (Wall clock time)')
(0.403238235429517, array([ 0.,  0.]), 'Execution took: 0:00:00 secs (Wall clock time)')
(1.625164876569622, array([ 0.,  0.]), 'Execution took: 0:00:00 secs (Wall clock time)')
(2.8470915177097273, array([ 0.,  0.]), 'Execution took: 0:00:00 secs (Wall clock time)')
(4.069018158849833, array([ 0.,  0.]), 'Execution took: 0:00:00 secs (Wall clock time)')
(16.288284570250884, array([ 0.,  0.]), 'Execution took: 0:00:00 secs (Wall clock time)')

使用odeint查找解决ODE的执行时间

1 个答案: