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https://issues.apache.org/jira/browse/SYSTEMML-1759?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16083412#comment-16083412
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Matthias Boehm commented on SYSTEMML-1759:
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yes, this should definitely be addressed; the same issues has been raised here:
https://www.mail-archive.com/[email protected]/msg00095.html
> make UDFs callable from expressions
> -----------------------------------
>
> Key: SYSTEMML-1759
> URL: https://issues.apache.org/jira/browse/SYSTEMML-1759
> Project: SystemML
> Issue Type: Improvement
> Components: Parser
> Affects Versions: SystemML 1.0
> Environment: IBM DataScience Experience
> Reporter: Romeo Kienzer
> Priority: Minor
>
> SystemML Parser stops with exeption:
> only builtin functions allowed as part of
> expression
> But the following re-write could be automated during parsing
> delta3 = -(Y-yHat) * sigmoidPrime(z3)
> =>
> smp = sigmoidPrime(z3)
> delta3 = -(Y-yHat) * smp
> Please consider the following code:
> script = """
>
> #
> sigmoid = function(matrix[double] z) return (matrix[double] z) {
> z = 1/(1+exp(-z))
> }
>
>
> sigmoidPrime = function(matrix[double] z) return (matrix[double] z) {
> #Gradient of sigmoid
> z = exp(-z)/(1+exp(-z))
> }
>
> X=matrix("3 5 5 1 10 2", rows=3, cols=2)
> inputLayerSize = 2
> outputLayerSize = 1
> hiddenLayerSize = 3
>
> W1 = rand(rows=inputLayerSize,cols=hiddenLayerSize)
> W2 = rand(rows=hiddenLayerSize,cols=outputLayerSize)
>
> feedForward = function (matrix[double] X,
> matrix[double] W1,
> matrix[double] W2) return (matrix[double]
> z2,matrix[double] z3,matrix[double] Y) {
> z2 = X %*% W1
> a2 = sigmoid(z2)
> z3 = (a2 %*% W2)
> Y = sigmoid(z3)
> }
>
>
> gradient = function(matrix[double] X,
> matrix[double] W1,
> matrix[double] W2,
> matrix[double] Y) return (matrix[double]
> dJdW1,matrix[double] dJdW1) {
> #Compute derivative with respect to W and W2 for a given X and y:
> [z2,z3,Yhat] = feedForward(X,W1,W2)
>
> delta3 = -(Y-yHat) * sigmoidPrime(z3)
> dJdW2 = t(a2) %*% delta3
>
> delta2 = (delta3 %*% t(W2))*sigmoidPrime(z2)
> dJdW1 = t(X) %*% delta2
> }
>
> [z2,z3,Yhat]=feedForward(X,W1,W2)
> nrx = nrow(X)
> ncx = ncol(X)
> nrw1 = nrow(W1)
> ncw1 = ncol(W1)
> """
> I'm getting a parser exeption saying that
> Caused by: org.apache.sysml.parser.ParseException:
> -------------------------------------------------------------- The following
> 2 parse issues were encountered:
> 1 [line 39:25] [Validation error] -> delta3 = -(Y-yHat) *
> sigmoidPrime(z3) only builtin functions allowed as part of
> expression
> 2 [line 42:32] [Validation error] -> delta2 = (delta3 %*% >
> t(W2))*sigmoidPrime(z2) only builtin functions allowed as part of
> expression
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