You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: dlagtm.go
    path of file: ./repos/gonum/lapack/gonum
    
    the code of the file until where you have to start completion: // Copyright ©2020 The Gonum Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package gonum

import "gonum.org/v1/gonum/blas"

// Dlagtm performs one of the matrix-matrix operations
//
//	C = alpha * A * B + beta * C   if trans == blas.NoTrans
//	C = alpha * Aᵀ * B + beta * C  if trans == blas.Trans or blas.ConjTrans
//
// where A is an m×m tridiagonal matrix represented by its diagonals dl, d, du,
// B and C are m×n dense matrices, and alpha and beta are scalars.
func (impl Implementation) Dlagtm(trans blas.Transpose, m, n int, alpha float64, dl, d, du []float64, b []float64, ldb int, beta float64, c []float64, ldc int) {
	switch {
	case trans != blas.NoTrans && trans != blas.Trans && trans != blas.ConjTrans:
		panic(badTrans)
	case m < 0:
		panic(mLT0)
	case n < 0:
		panic(nLT0)
	case ldb < max(1, n):
		panic(badLdB)
	case ldc < max(1, n):
		panic(badLdC)
	}

	if m 
    
func (impl Implementation) Dlagtm(trans blas.Transpose, m, n int, alpha float64, dl, d, du []float64, b []float64, ldb int, beta float64, c []float64, ldc int) {
	switch {
	case trans != blas.NoTrans && trans != blas.Trans && trans != blas.ConjTrans:
		panic(badTrans)
	case m < 0:
		panic(mLT0)
	case n < 0:
		panic(nLT0)
	case ldb < max(1, n):
		panic(badLdB)
	case ldc < max(1, n):
		panic(badLdC)
	}

	if m == 0 || n == 0 {
		return
	}

	switch {
	case len(dl) < m-1:
		panic(shortDL)
	case len(d) < m:
		panic(shortD)
	case len(du) < m-1:
		panic(shortDU)
	case len(b) < (m-1)*ldb+n:
		panic(shortB)
	case len(c) < (m-1)*ldc+n:
		panic(shortC)
	}

	if beta != 1 {
		if beta == 0 {
			for i := 0; i < m; i++ {
				ci := c[i*ldc : i*ldc+n]
				for j := range ci {
					ci[j] = 0
				}
			}
		} else {
			for i := 0; i < m; i++ {
				ci := c[i*ldc : i*ldc+n]
				for j := range ci {
					ci[j] *= beta
				}
			}
		}
	}

	if alpha == 0 {
		return
	}

	if m == 1 {
		if alpha == 1 {
			for j := 0; j < n; j++ {
				c[j] += d[0] * b[j]
			}
		} else {
			for j := 0; j < n; j++ {
				c[j] += alpha * d[0] * b[j]
			}
		}
		return
	}

	if trans != blas.NoTrans {
		dl, du = du, dl
	}

	if alpha == 1 {
		for j := 0; j < n; j++ {
			c[j] += d[0]*b[j] + du[0]*b[ldb+j]
		}
		for i := 1; i < m-1; i++ {
			for j := 0; j < n; j++ {
				c[i*ldc+j] += dl[i-1]*b[(i-1)*ldb+j] + d[i]*b[i*ldb+j] + du[i]*b[(i+1)*ldb+j]
			}
		}
		for j := 0; j < n; j++ {
			c[(m-1)*ldc+j] += dl[m-2]*b[(m-2)*ldb+j] + d[m-1]*b[(m-1)*ldb+j]
		}
	} else {
		for j := 0; j < n; j++ {
			c[j] += alpha * (d[0]*b[j] + du[0]*b[ldb+j])
		}
		for i := 1; i < m-1; i++ {
			for j := 0; j < n; j++ {
				c[i*ldc+j] += alpha * (dl[i-1]*b[(i-1)*ldb+j] + d[i]*b[i*ldb+j] + du[i]*b[(i+1)*ldb+j])
			}
		}
		for j := 0; j < n; j++ {
			c[(m-1)*ldc+j] += alpha * (dl[m-2]*b[(m-2)*ldb+j] + d[m-1]*b[(m-1)*ldb+j])
		}
	}
}