Error finding matrix indices where elements obey a condition

Hi,

I have a (30,1) matrix A filled with both positive and negative double values with high precisions.

I do the B= A>0 expecting a resulting matrix filled with 0s and 1s based on the value of original matrix such as

[0,
0,
1,
1,
0,
....]

However, when I display I get a matrix like below

0.0 < -60.80089912054130723383673691361028456512560544254638307756720395046146077078219605027697980403900146484375

0.0 < -40.47441497086561319883182687840919573785507473004455923328153712191512791918057700968347489833831787109375

0.0 < 11.9150901590727927897158716535914255438713276913571208738565018227240077663964257226325571537017822265625

0.0 < 50.24337655630030618369864852262179095255359883940103235308691394245261818696235422976315021514892578125

0.0 < -12.788094842081277874683606597932106962408104528383932295293478643982698628178695798851549625396728515625

0.0 < -19.7994345791724984686511623375698392780606832842132285447736268595153585891921466100029647350311279296875

0.0 < 44.20960440529531749044620672799080999950637846265719961065220598196712220584458918892778456211090087890625

0.0 < -38.4752715808701180299125340913012275096601820744906678455217984013980725421788520179688930511474609375

0.0 < -57.1261686699021779161260124218737353314343618323505877827184033790341999292650143615901470184326171875

0.0 < -15.50675798085333259859508957067109961395543474125240585269404109021451620975540208746679127216339111328125 0

Later when use matrix B in a matrix multiplication I get a lot of NaN values. Where am I doing wrong? I will be very appreciated if I can find a solution dfor this . Cause I am struggling due to this issue for a few days..

Best Regards,

Ferda

[madhan ravi]

please attach your 30 by 1 matrix as a .mat file

[ferda sonmez]

I attached. However, when I look mat file I saw a content like

1x1 sym

1x1 sym

1x1 sym

....

I don't know what this points out.. Thank you for your interest.

[Luna]

Ferda, what is the source of your saved .mat file? Did you saved it yourself from your workspace?

[ferda sonmez]

yes I saved it usign the below code

save("Matrix_Saved.mat", 'input_of_hidden_layer2');

[Luna]

As far as I understand your data already symbolic in your workspace. You should convert it into double array see my answer below.

You can also convert it before saving, when you load you will get the double array instead of symbolic array.

A = double(input_of_hidden_layer2)
save('SavedMatrix1.mat','A')

load('SavedMatrix1.mat') % you will see A 30x1 double in your workspace. 

[madhan ravi]

When you use vpa() or vpasolve() the class of the variable becomes symbolic.

[Luna]

Ah now I understand, thx :)

Answer 1

[Luna]

Hi Ferda,

Please see my comments below:

% first convert it to double array:
A = double(input_of_hidden_layer2);
% indexing your conditions:
B = A > 0;
% get the values which are greater than zero from that index:
A(B)

[ferda sonmez]

Thank you for your answer :)

[Luna]

Your welcome :)

Answer 2

[Walter Roberson]

B = isAlways(A>0);

will give you a logical result. Or you could

B = logical(A>0);

[Luna]

+1 :)