Esempio: Funzioni di ottimizzazione

Blocchi di soluzione > Esempio: Funzioni di ottimizzazione

Questo esempio mostra come passare un vettore di valori ipotizzati alla funzione Maximize o Minimize.

1. Definire la funzione f(x).

2. Definire x come vettore di valori ipotizzati.

3. Passare il vettore x come argomento alla funzione Maximize.

L'errore si verifica perché PTC Mathcad si aspetta che x sia un valore singolo e non un vettore.

Per evitare questo errore, è necessario scorrere i valori ipotizzati e inviarli uno alla volta alla funzione Maximize, come illustrato di seguito.

4. Utilizzare l'operatore di intervallo per definire un vettore di valori ipotizzati.

Fare clic per copiare questa espressione

5. Definire due nuove funzioni per eseguire maximize e minimize nella funzione f(x).

6. Scrivere un breve programma per scorrere i valori ipotizzati e calcolare il valore massimo e minimo per il valore ipotizzato e salvare il risultato rispettivamente nei vettori maximums e minimums.

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    <define xmlns="http://schemas.mathsoft.com/math50">
      <id labels="VARIABLE" xml:space="preserve">Ms</id>
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                <id labels="VARIABLE" xml:space="preserve" label-is-contextual="true">Vec</id>
              </apply>
              <real>1</real>
            </apply>
          </range>
          <program>
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                <indexer />
                <id labels="VARIABLE" xml:space="preserve">maximums</id>
                <id labels="*" xml:space="preserve">i</id>
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              <apply>
                <id labels="VARIABLE" xml:space="preserve" label-is-contextual="true">F</id>
                <apply>
                  <indexer />
                  <id labels="VARIABLE" xml:space="preserve" label-is-contextual="true">Vec</id>
                  <id labels="VARIABLE" xml:space="preserve" label-is-contextual="true">i</id>
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            </localDefine>
            <localDefine>
              <apply>
                <indexer />
                <id labels="VARIABLE" xml:space="preserve">minimums</id>
                <id labels="*" xml:space="preserve">i</id>
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              <apply>
                <id labels="VARIABLE" xml:space="preserve" label-is-contextual="true">G</id>
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                  <indexer />
                  <id labels="VARIABLE" xml:space="preserve" label-is-contextual="true">Vec</id>
                  <id labels="VARIABLE" xml:space="preserve" label-is-contextual="true">i</id>
                </apply>
              </apply>
            </localDefine>
          </program>
        </for>
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          <id labels="VARIABLE" xml:space="preserve" label-is-contextual="true">maximums</id>
          <id labels="VARIABLE" xml:space="preserve" label-is-contextual="true">minimums</id>
        </matrix>
      </program>
    </define>
    <resultFormat>
      <matrix size="12,12" offset="0,0" show-indices="false" expand-nested-arrays="false" />
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È possibile ottenere lo stesso risultato utilizzando l'operatore di vettorizzazione, come indicato di seguito:

Entrambi Ms e Qs restituiscono un vettore di due vettori di 7 elementi contenente i valori massimi e minimi calcolati.

7. Definire una variabile j come la lunghezza del vettore restituito di valori massimi.

8. Tracciare il grafico della funzione f(x) insieme ai punti massimo e minimo restituiti dal programma.

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9. Tracciare il grafico della funzione f(x) insieme ai punti massimo e minimo restituiti dall'operatore di vettorizzazione.

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