Error, (in sum) expecting two arguments - Maple Programming Help

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Error, (in sum) expecting two arguments

 

Description

Compatibility

Examples

See Also

Description

A correctly defined sum requires a summand and the index or index range of summation. This error occurs when one of these arguments is not provided.

Compatibility

Note: As a result of updates made in Maple 15, this error message appears in Maple 14 and earlier versions.

Examples

Example 1

In the following example, it is unclear whether the argument i represents the summand or the index.

sumi

Error, (in sum) expecting two arguments

 

Solution:

For this example, we assume the intention was for the summand and index to both be i.  You must explicitly state both arguments for sum.

sumi,i

12i212i

(3.1)

Example 2

In the following example, attempting to sum more than one summand at a time results in an error.

sumi2,i,i

Error, (in sum) expecting two arguments

 

Solution:

To sum more than one summand at at time, use the map command.

mapsum,i2,i,i

13i312i2+16i,12i212i

(3.2)

Example 3

In the following example, attempting to calculate the sum of i+j  over both index variables results in an error. This statement is not well-defined.

sumi+j,i=1..3,j=6..8

Error, (in sum) expecting two arguments

 

Solution:

Depending on the interpretation, one possible solution is to express the sum in the following manner:  if the indices are meant to be sequenced individually, then the following statement corrects the error and produces the intended result.

sumsumi+j,i=1..3,j=6..8

81

(3.3)

Otherwise, if the indices are meant to be sequenced in tandem, then the following statement corrects the error and produces the intended result.

sumevali+j,j=i+5,i=1..3

27

(3.4)

See Also

 eval,  map, sum


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