round off problem in matlab

I have 4 variables each have 4 values (1x4) in it and I want to store all in value in 1 variable (4x4) but values are change when i do it.

MAV = [0.0924317411754942 0.0313003411430704 0.00365072354007141 0.00332056432198707]

waveLen = [172.697769103870 68.7603283596702 69.2536410243476 63.2141284111186]

zcdOut = [560 719 6155 6260]

slope_count = [478 212 4949 4830]

HG0_extracted_feature = [waveLen; MAV; zcdOut; slope_count]

it gives

173 69 69 63

0 0 0 0

560 719 6155 6260

478 212 4949 4830

note MAV values become zero, it round off waveLen, etc values...

how i correct it?

Thank you

Answer 1

[Steven Lord]

Based on that display I suspect one or both of the variables zcdOut or slope_count are stored in an integer class. When you combine data stored in an integer class with data stored in a non-integer class, "all elements of the resulting matrix are given the data type of the left-most integer".

Consider converting the variable stored in an integer class to double before combining them into one array, so that the resulting matrix is also a double.

[Ali Asghar]

how i check the type of variable of zcdOut and slope_count?

how i convert it into double ?

[Stephen23]

"how i convert it into double ?"

https://www.mathworks.com/help/matlab/ref/double.html

[Steven Lord]

Check the types of variables using class or whos.

As Stephen Cobeldick said, to convert variables to double use the double function.

[Ali Asghar]

thanks dear

Answer 2

[Raj]

Just add 'format longg' before your code like this:

format longg
MAV = [0.0924317411754942	0.0313003411430704	0.00365072354007141	0.00332056432198707]
waveLen = [172.697769103870	68.7603283596702	        69.2536410243476	          63.2141284111186]
zcdOut = [560	719	6155	6260]
slope_count = [478	  212	4949	4830]
HG0_extracted_feature = [waveLen; MAV; zcdOut; slope_count]

Read about format here:

https://www.mathworks.com/help/matlab/matlab_prog/display-format-for-numeric-values.html

[Ali Asghar]

Dear i have data called filter_datawindow 24000x4.

i apply functions in loop that store the value of waveLen, MAV, zcdOut, slope_count in workspace in long format but when i merge all values is give same result as

173 69 69 63

0 0 0 0

560 719 6155 6260

478 212 4949 4830

for i = 1:4

waveLen(i) = find_waveform_length(filter_datawindow(:,i))

MAV (i)=find_MAV(filter_datawindow(:,i),2.4e4)

zcdOut (i) = zcd(filter_datawindow(:,i));

slope_count (i) = find_slopSign(filter_datawindow(:,i),0.001)

end

format longg

HG0_extracted_feature = [waveLen; MAV; zcdOut; slope_count]

gives

173 69 69 63

0 0 0 0

560 719 6155 6260

478 212 4949 4830

Answer 3

[Matt J]

The values are not changed. They are just displayed to the screen to 4 decimal points. Use format long to see more precision. Also, note that all elements are premultiplied by 1000.

[Ali Asghar]

when i merge all values it gives

173 69 69 63

0 0 0 0

560 719 6155 6260

478 212 4949 4830

instead of

172.69776910387 68.7603283596702 69.2536410243476 63.2141284111186

0.0924317411754942 0.0313003411430704 0.00365072354007141 0.00332056432198707

560 719 6155 6260

478 212 4949 4830

[Matt J]

As Steven. mentioned, that is probably because one of the vectors you are merging is uint8 or similar.

[Steven Lord]

Rows 3 and 4 of the resulting array have values too large for uint8 or int8 so they would need to be at least 16-bit integers.