MATLAB: Numerical answer required for sumation

sinsingle valuesummation

a very basic question, say i use

symsum(((-1)^(sym('k')-1))*(sin(sym('k'))), k, 0, 12)

I just get

sin(311/250) – sin(311/125) – sin(311/625) – sin(622/625) – sin(933/625) + sin(311/1250) – sin(1244/625) + sin(933/1250) – sin(1866/625) + sin(2177/1250) + sin(2799/1250) + sin(3421/1250)

but i want a single numeric value (like 0.2354 or whatever) not this expanded string of sin's. I dont want like 0.254 +0.056 +0.214 etc I just want a single value.

Ive tried searching on google but i have the normal problem of not knowing what the keyword is to search for.

Best Answer

You can apply double() to a symbolic expression to get back the Matlab double precision number that is equivalent.

If you want the result to be a symbolic number instead, such as if you need to evaluate to more decimal places, then use vpa() on the symbolic expression.

Related Solutions

MATLAB: I have an array of data from a sensor which varies from positive to negative continuously. I want to find the peak value of each set of positive numbers and negative numbers.

>> findpeaks(X(X>0))
ans =
  Columns 1 through 10
    4.5190    4.5260    3.3360    3.1910    2.4630    1.8080    1.7910    1.3260    1.0030    0.7530
  Columns 11 through 20
    0.5650    0.4140    0.3060    0.3030    0.2290    0.2280    0.1710    0.1710    0.1300    0.1180
  Columns 21 through 30
    0.0980    0.0740    0.0520    0.0540    0.0410    0.0410    0.0320    0.0250    0.0190    0.0200
  Columns 31 through 40
    0.0020    0.0150    0.0150    0.0150    0.0110    0.0110    0.0110    0.0110    0.0070    0.0080
  Columns 41 through 50
    0.0090    0.0090    0.0090    0.0020    0.0040    0.0070    0.0020    0.0030    0.0030    0.0040
  Columns 51 through 59
    0.0050    0.0020    0.0020    0.0030    0.0030    0.0030    0.0030    0.0020    0.0020
>> abs(findpeaks(-X(X<0)))
ans =
  Columns 1 through 10
    3.8980    3.7790    2.8760    2.1120    2.1030    1.5570    1.5540    1.1540    0.8550    0.6340
  Columns 11 through 20
    0.4610    0.4700    0.3490    0.2600    0.1950    0.1450    0.1090    0.0790    0.0810    0.0590
  Columns 21 through 30
    0.0600    0.0600    0.0450    0.0450    0.0340    0.0270    0.0270    0.0200    0.0150    0.0150
  Columns 31 through 40
    0.0150    0.0100    0.0030    0.0100    0.0100    0.0100    0.0020    0.0060    0.0060    0.0060
  Columns 41 through 50
    0.0060    0.0050    0.0040    0.0020    0.0040    0.0040    0.0040    0.0040    0.0020    0.0020
  Columns 51 through 60
    0.0020    0.0020    0.0030    0.0030    0.0020    0.0020    0.0020    0.0020    0.0020    0.0020
  Columns 61 through 64
    0.0020    0.0020    0.0020    0.0020
>>

findpeaks is in Signal Processing Toolbox...

MATLAB: How to generate Combination of special sets and subsets

This is called a circulant matrix. I have written a function that can be found in the File Exchange:

A = [100 125 300 400]
B = circulant(A,-1)
tf = flipud(tril(true(size(B))))
C = B(tf)

CIRCULANT can be downloaded here: http://www.mathworks.com/matlabcentral/fileexchange/22876

Best Answer

Related Solutions

MATLAB: I have an array of data from a sensor which varies from positive to negative continuously. I want to find the peak value of each set of positive numbers and negative numbers.

MATLAB: How to generate Combination of special sets and subsets

Related Question